It seems the steam sale's finally pushed me off the deep end and driven me to build a gaming PC. The only problem is I have absolutely no idea what I'm doing when it comes to computers; I've read several guides to building your own rig, but I still can't determine what the numbers in a part's tech specs mean, or whether two separate parts are compatible. My fallback has been to go onto newegg, and choose one of the most expensive item from each category, assuming that it is also the best for my needs (i.e. running current gen games on their highest settings). I'm begininning to question my logic however, so I thought I'd consult some bombers before proceeding any further. Here is what my ill-conceived frankenstein of parts looks like as of now. 

um that ram doesnt look priced right so it could be crappy go for corsair ram like dominators a little more expensive but very good, and i would say get 2 1 tb drives so you have one for back up and 1 tb is enough for some time, i have 1 and an external hdd for backup and i still have 500 gigs left and i have a bunch of games and music

Well, think about it like this.

If you play a lot of PC games, and you have the disposable income, consider starting at $1500 for a pretty top end gaming PC. This would be a complete system independent of your current one.

If you don't play so many PC games or if money's tighter, think instead about buying an upgrade for your current computer. $600 invested into a reasonable existing rig can yield a huge benefit.

Finally, the areas I would consider from MOST IMPORTANT to least important are:

• Video Card: If the computer is for gaming, this should probably be the most expensive thing you invest it. A high end video card (sometimes called a GPU) will almost always yield the biggest performance improvement
• RAM: Most modern games handle fine on 6 gigs of decent RAM. 8 is a good amount from what I see above.
• CPU: Most 3D games are more memory and GPU-intensive than CPU intensive, so any reasonably priced quad core around or above 2.4ghz will have you set to play most anything
• Cooling: This is sometimes overlooked by people building a PC for the first time, but a good case and extra fans (which can often be installed for you) can make a huge difference. Try to find out if the GPU that you are buying runs especially hot, and if it does consider a case that has good cooling options or extra fans for better airflow
• Motherboard: Most modern, mainstream motherboards are pretty reliable but always look up beforehand to see if what you're purchasing is working out for other customers.
• Hard Drive: Consider investing in a 7200rpm hard drive. An added luxury is a solid state boot drive, keeping your regular hard drive(s) for everything other than Windows
• Power Supply: 750w should be good, unless you plan on overclocking anything (doesn't sound like it)
• Sound Card: I don't even have one of these yet! Then again, I don't use speakers, so I can't comment. Probably a good idea

it's in your best interest to ditch the hitachi hdd and replace it with a western digital caviar black.

Yeah, I've heard that the 2500K is plenty if you're only going to be gaming, I think the 2600 is more for video editing and other stuff. That case is pretty pricey, you might want to find a cheaper one if you don't really care about shiny, flashy cases. Sound card is probably not necessary, I think it's more for those who really care about good audio. 3TB seems overboard for a hard drive, maybe look into an SSD for faster boots and then buy a 1TB hard drive.

Here are a couple of links that should definitely get you going in the right direction.  This video and thread will help you with almost all of you questions.

That's an awesome rig, but if you stick with a 5400rpm hard drive you will seriously limit the performance. You have picked a great motherboard with a special trick up its sleeve, but the get the most out of it you need to get a high performance HDD like a WD Caviar Black or a Samsung Spinpoint (I would suggest 1 to 1.5tb) and you really should have a 60gb SSD, the fastest on the market are the Agility 3's by OCZ, but the Intel 320 drives are pretty good too if you can wait for the next firmware update that will fix a software issue in these.
 
About the trick, SSDs offer excellent read and write speeds, much faster than normal hard drives but the trade off is limited storage, you can't do much with 60gb. Your mobo has a special feature called SRT which lets the SSD work as a cache, to use it you install Windows onto your normal drive and then set up the SSD as an SRT drive. This looks at you normal drive and copies the most used files onto the SSD so they load at SSD speeds. The trade off here is that only read speeds will be super fast, all writing is done to the hard drive and then copied to the SSD if it is a frequently used application or file. But as you will spend more time reading files than writing them that might not be a massive downside, the benefits to this appraoch is that it is a fire and forget solution, you don't need to manage the system but can enjoy the benefits all the time, like start up times taking less than 40 seconds instead of around 2 to 3 minutes.
 
@BUCK3TM4N: Kingston HyperX is pretty good ram, the reason it looks cheap is that ram has pretty much dipped to a record low at the moment, buy now while you can get it cheap as prices will go up as supplies dry up due to manufacturers slowing down production to regulate pricing.