Ok, so as the title states I'm building a gaming PC.  This is my second time building one, but the first time I did it with a friend who was very knowledgeable with PC parts.  I know a decent amount.  I wouldn't say I'm a whiz, but I do know a lot more than the normal person. 
  
My Reason:  I like PC games because obviously on the graphics end they are a lot better, but also because of the mods, more precision, more flexibility, and I feel like it's more personal since I'm a lot closer to the monitor and what not.  About 3 years ago I had a Dell XPS 720 with the best specs you can imagine at the time.  Quadcore when it first came out.  So I'm familiar with PC gaming and the technology.  I sold it since windows Vista made it run like shit and because most of my friends played 360 and I would have friends over basically every day.  Now with college and everything I don't need to worry about that.  The main reason was mostly Vista and I switched to a Mac because of that and I don't plan on switching back.

My Objective:  Build a gaming PC in the $2,000 price range that can play games on max settings and that will last for 2-3 years, I do not mind upgrading video card yearly.  I want to make sure that with the motherboard I have it is easily upgradeable for the future.  I will only be using this computer for gaming since I have an iMac and there is no way I'm going back to windows for general use and video editing.  
 
Parts:
 
CPU: Intel Core i7 920 2.66GHz
 
Motherboard: EVGA X58
 
RAM: Corsair Dominator  6GB (3x2GB) DDR3 1600MHz 
 
Video Card: 2X Radeon 5850 or 2X nVidia GTX 275 1.7GB
 
HDD: 1.5TB Western Digital 7,200 RPM 32MB Cache
 
Sound Card: Creative X-Fi Titanium 
 
Optical Drive: LiteOn 24x DVD-R
 
OS: Windows XP Professional SP3 / Windows 7
 
PSU: Corsair 850W 
 
Case: Silverstone Raven RV01
 
Other Thoughts / Questions:  Please make recommendations for other parts.  Since it is a gaming PC I don't want to go with budget parts.  I am flexible with the price even though I would like to keep it around the $2,000 price range.  Also I haven't been on top of the PC hardware so is nVidia still better than ATI for video cards?  I know that Intel blows AMD out of the water.  Which pair of video cards listed should I buy?  On paper it looks like ATI is better, but tests are mixed.  How is the crossfire support compared to SLI?
 

Looks good, but maybe go with 6GB of RAM. I read somewhere that multiples of 3 work better with i7 mobos, but don't quote me. 

Looks good, but maybe go with 6GB of RAM. I read somewhere that multiples of 3 work better with i7 mobos, but don't quote me.

" Looks good, but maybe go with 6GB of RAM. I read somewhere that multiples of 3 work better with i7 mobos, but don't quote me.  "

" @Giantsquirrel said:

" Looks good, but maybe go with 6GB of RAM. I read somewhere that multiples of 3 work better with i7 mobos, but don't quote me.  "

I would, but I am using Windows XP 32Bit so 4GB, well actually 3.25GB is the most supported.  I think I do have a 64bit CD laying around somewhere.  I have used Windows XP 64Bit before, but had a lot of problems with it. "

" @j_drace: 
Doesn't seem like a bad bunch of choices so far, but 2xGTS 250 seems like a really inefficient choice to me.  Better to buy a higher end single GPU solution.
 
You won't be able to take advantage of higher end DX10 or DX11 graphics features without Vista or Windows 7.  I'd recommend moving on.
 
Is your copy of Windows XP 64-bit?  You should get a 64-bit OS to utilize 4GB of RAM (which is a good amount).  Otherwise you'll only have 2GB-3GB or so available for programs.
 
If you do move on to Windows 7 or Vista you probably won't need the X-Fi sound card, as changes in Windows Audio have kind of cut out the advantages of the X-Fi tech (but not completely).
 
That case seems crazy expensive to me, I just don't think you should spend that much on a case.
 
@Giantsquirrel said:

Looks good, but maybe go with 6GB of RAM. I read somewhere that multiples of 3 work better with i7 mobos, but don't quote me.

I don't have a DDR3 mobo myself, but maybe has to do with putting your RAM into triple channel?  I'm not certain about that tech myself.  Probably would be good to do, if that's how it works. "

I haven't taken a close look yet but there must be something wrong with your build, I have  
 
i7 920 
GTX 275 SLI 
6GB DDR3 1600 
1TB HDD
24" Monitor 
 (and other required parts)
For 2k altogether. That is better than what you have and I bought it half a year ago. I might be able to take a closer look later but for now all I can suggest is upgrade your graphics setup, GTS 250 SLI is good value but poor in terms of absolute performance. You could probably shave off a few hundred dollars from your case, mouse, keyboard and monitor and spend that money on the thing that really matters, the graphics setup. By doing so you could probably get double the performance than what you would get currently, at the same price. 

" I haven't taken a close look yet but there must be something wrong with your build, I have   i7 920 GTX 275 SLI 6GB DDR3 1600 1TB HDD24" Monitor  (and other required parts)For 2k altogether. That is better than what you have and I bought it half a year ago. I might be able to take a closer look later but for now all I can suggest is upgrade your graphics setup, GTS 250 SLI is good value but poor in terms of absolute performance. You could probably shave off a few hundred dollars from your case, mouse, keyboard and monitor and spend that money on the thing that really matters, the graphics setup. By doing so you could probably get double the performance than what you would get currently, at the same price.  " @Geno:

" @Geno said:

" I haven't taken a close look yet but there must be something wrong with your build, I have   i7 920 GTX 275 SLI 6GB DDR3 1600 1TB HDD24" Monitor  (and other required parts)For 2k altogether. That is better than what you have and I bought it half a year ago. I might be able to take a closer look later but for now all I can suggest is upgrade your graphics setup, GTS 250 SLI is good value but poor in terms of absolute performance. You could probably shave off a few hundred dollars from your case, mouse, keyboard and monitor and spend that money on the thing that really matters, the graphics setup. By doing so you could probably get double the performance than what you would get currently, at the same price.  " @Geno:

Thanks for the recommendation.  I looked into that and have updated my specs now.  I'm going to buy a GTX 275 1.8GB and then in about 2 weeks once I save up enough money buy the second one.  Also I settled for that CPU, but I chose to go with the 4GB RAM instead of 6GB since I don't know when exactly I will be updating to Windows 7.  I'm still keeping the case and monitor, LOL. "

switch your mobo to X58 (for future proofness) and also usb 3.0 (nothing uses it yet, but, believe me, they will be)
 
switch your GPU to an ATI 5870 (or 5970 if you have the money) 
 or wait for the 300 series nvidia's to come out.  
it's a waste of money to get anything in the 200 series because it's about the same price as nvidia's new cards but there's no directx11 and have lower specs.

you're getting ripped off on the memory, if you're gonna spend that much you might as well get 6 gb's (3 x 2gb ddr3) 

and dude. 
windows 7. 
seriously.   
64 bit rules, especially with 4 or more gb's of ram (which xp 32 doesn't support) and a multicore processor like the core i7.  staying with XP would just be a waste, because you cant even get the full performance out of your fancy new PC.

" @Diamond: I've had 64Bit Windows Vista Ultimate and it completely sucked.  The biggest waste of $300. "

" @Geno: I'm not going with ATI nor am I going with Windows 7 right away.  I used to have a ATI 1800XT 512MB like 4 years ago when they first came out and I didn't really like it much.  I prefer nVidia if the 300 series launch within a month or so then I may get them instead.  As for Windows 7, I've used it and I'm not really that impressed with it.  I'm not jumping on the DX11 bandwagon either because I did jump on the DX10 bandwagon when that came out and it wasn't much of an improvement.  So I'm going to be sticking with XP until Windows 7 really catches my eye.  WIth that being said IDK if you read my entire post or at least past the parts section, but this PC is only for gaming since I have an iMac. "

I suggest going with the Radeon HD5870 it seems to be the best graphics card out atm, (if you dont count the HD5970 because of its driver issues.)  it supports direct X 11 as well so, like the poster above says, go with windows 7 64bit. This site may be of interest 
http://www.bit-tech.net/hardware/buyers-guide/2010/01/11/what-hardware-should-i-buy-january-2010/4

My Objective:  Build a gaming PC in the $2,000 price range that can play games on max settings and that will last for 2-3 years.

CPU: Intel Core i7 920 2.66GHz ( http://www.newegg.com/Product/Product.aspx?Item=N82E16819115202 ) - $289

Motherboard: EVGA P55 ( http://www.newegg.com/Product/Product.aspx?Item=N82E16813188055 ) - $190

RAM: Corsair Dominator  4GB (2x2GB) DDR3 1600MHz ( http://www.newegg.com/Product/Product.aspx?Item=N82E16820145249 ) - $146

Video Card: EVGA nVidia GTX 275 1.8GB 256Bit ( http://www.amazon.com/exec/obidos/tg/detail/-/B0028ACU5I/ref=ord_cart_shr?_encoding=UTF8&m=A1KG6QISTB45M0&v=glance ) - $320

HDD: Western Digital Black 640GB 7,200 RPM ( http://www.newegg.com/Product/Product.aspx?Item=N82E16822136319 ) - $75

Sound Card: Creative X-Fi Titanium  ( http://www.newegg.com/Product/Product.aspx?Item=N82E16829102024 ) - $100

OS: Windows XP Professional SP3 - I already have the CD

First thing first.  That motherboard is an 1156 slot and not a 1366.  It does not support an i7 920, get something else.
 
Secondly,  getting 4 GB is a waste for that setup especially since your insistent on not using Windows 7 x64 (which you can find for $30 if you're a student) or Vista x64.  You might as well get 3 sticks of 1 GB for a total of 3 GB and then upgrade to 6 GB down the line.  This would also mean you probably should get a board that has the 6 ram slots rather than 4.
 
It seems that you want help, but won't really accept any, weird.

Drop your sound card and get a 60GB Solid state drive, run your OS off that. In regards to Mobo, I personally got an Intel P6T, it'll support your chip and runs beautifully.

" First thing first.  That motherboard is an 1156 slot and not a 1366.  It does not support an i7 920, get something else.   Secondly,  getting 4 GB is a waste for that setup especially since your insistent on not using Windows 7 x64 (which you can find for $30 if you're a student) or Vista x64.  You might as well get 3 sticks of 1 GB for a total of 3 GB and then upgrade to 6 GB down the line.  This would also mean you probably should get a board that has the 6 ram slots rather than 4.  It seems that you want help, but won't really accept any, weird. "

If I do go with Windows 7 is 6GB RAM enough or should I go with 12?

6 should be fine, even for really RAM intensive tasks liked editing video in HD.  I find my 4GB is barely stretched and I make music.

6gig is just dandy for you average 1366 socket user, only people who need that sort of ram are video editors, graphic designers and people like myself who run VM environments. Grab Win7 64-bit, it's great and works splendidly (and it's not like it costs any more than the 32-bit variety), I've been using it a while now and its a fantastic OS.  I'd suggest maybe taking a look at the ATI Radeon 5850 over the GTX 275, the 275 is a great card to be sure but the 5850 is a little quicker and has full DX11 support (DX11 API's are to be included in titles launching soon like AVP3 and Battlefield BC2), also it packs a few extra bells and whistles (eyefinity, hdmi out with full 7.1 LPCM audio).

 http://www.hardocp.com/article/2009/09/30/amds_ati_radeon_hd_5850_video_card_review
 
Theres a review from my normal "go to" tech site if your interested.

UPDATED PARTS.  With the current parts I have listed how will the PC perform with games like Dragon Age: Origins and Crysis Warhead on a resolution of 1650x1080 or 1920x1200?  How will it perform on those resolutions with only one video card as opposed to two?

I'd reccomend you snag Windows 7 instead of XP. As great as XP is, you won't be able to take full advantage of that hardware on it. On top of that CrossfireX is many times better then SLI, at least where performance-per-card is concerned. 
To answer your last question: To get an idea how two 5850's will run, check out this review. Dragon Age should not be a problem, by the way.

" UPDATED PARTS.  With the current parts I have listed how will the PC perform with games like Dragon Age: Origins and Crysis Warhead on a resolution of 1650x1080 or 1920x1200?  How will it perform on those resolutions with only one video card as opposed to two? "

CPU: Intel Core i7 920 2.66GHz

" @j_drace said:

CPU: Intel Core i7 920 2.66GHz

Dont know if it matters to you but the Core i5 runs pretty much the same as the i7 and is a lot cheaper you may want to check it out "

You still need to pick a Heat Sink.  A word of advice, some of the heat sinks meant for the chipset that i7s belong to have two layers of protective film on the bottom.  A friend and I both made the mistake of only removing one layer for both of our computers and had the processors running at temperatures much higher than acceptable.  We didn't end up doing damage to them (I'd assume credit is due to Intel for that), but i7s should idle around 30C (in an average circulation case with a good heat sink) and and hit around 60C when running at full load.

You don't need a heat sink unless your over clocking, the stock cooler will be just fine if your running the chip at stock speeds.

" You don't need a heat sink unless your over clocking, the stock cooler will be just fine if your running the chip at stock speeds. "

" @Korwin said:

" You don't need a heat sink unless your over clocking, the stock cooler will be just fine if your running the chip at stock speeds. "

This; and even if you do overclock you're going to need at least a water cooling unit.  "

" @Geno said:

" @Korwin said:

" You don't need a heat sink unless your over clocking, the stock cooler will be just fine if your running the chip at stock speeds. "

This; and even if you do overclock you're going to need at least a water cooling unit.  "

No, you don't.  There are a number of air coolers that can perform on par with watercooling i.e. the TRUE (Thermalright Ultra Extreme) or the Xigamatek Dark Knight. "

2 Video Cards seems like over kill to me, but it is a gaming PC...
 
If you spend less on the video card(s), you won't a have such a hard time upgrading to a new video card in 18 months....

Water is really only for the most hard core, I run my 920 at 4.02 so I use water.  If your dead set on after market cooling for whatever reason i would recommend the Cogage True Spirit, 95% the performance of a Thermalright True but it costs a good chunk less.

@j_drace from everything I've heard, technically water cooling should work fine - if built by someone competent. 
 
That said, I wouldn't have it my system.  I'll put up with the fan noise, and stay dry.
 
Tom's Hardware talks about stuff like water cooling, i think.
 http://www.tomshardware.com/forum/253958-29-watercooling-guide

" @Geno:   People have been able to push the i7 920 on air to 4 ghz.  Again, it really depends on the heatsink, but it's completely doable and cheaper than liquid cooling. "  

Liquid cooling is only reasonably similar in price to Air HSFs when you look at something the Corsair H50 and that's only comparable in price to some of the more expensive air HSFs.  It's a convenient solution because you don't have to by a radiator, fan, pump and piping separately, but it doesn't compare with proper waterblock kits, for one you can't also cool your GPU(s) with the H50 and it's about equal in comparison with similarly priced air cooling solutions.
 
Something like a Hyper TX3 is a nice cheap air cooler for those who only want a marginal overclock or who live in cooler ambient conditions and can easily push their CPUs harder.

Looks fine if you want to spend that much, but for the love of god dont buy a Creative X-Fi Titanium.The drivers are so bad.If you really need a soundcard get the forte.