Alright, the time has come to buy my first new computer in going on three years. At the moment I'm using an ancient Lenovo I bought from Office Depot my senior year of college. As you can imagine it is not a graphical or processing powerhouse. Heck, it doesn't even have Windows Vista. Looking at the large number of MMOs which have been released in ensuing years and the quick (at least I hope) approach of The Old Republic and Starcraft II I'm thinking it's time to upgrade. I'm not looking for something horrifically expensive as I have student loans that are going to slowly kill me. 
 
Something in the couple thousand dollar range at the most which will last me two or three years would be just fine. I know tons about console gaming but when it comes to the PC side of things I am almost clueless. At the moment I'm looking around sites like Alienware to see some of their pre-builds but I have no idea what's better than another.
 
So, does anyone have any advice?

$2,000 will get you a pretty  bad ass computer.... so go core i7 and maybe a 5870 and crossfire it someday!

Wow, thats alot of cash, I would definitely look around.  If you can build it yourself, it is usually cheaper.  Stores online and real will vary ALOT with their prices, so don't jump the gun.  
http://www.cyberpowerpc.com/landingpages/intel/i7/
This was first link I saw with somewhat reasonable prices.
GL

Well, I figured the expression go big or go home would apply well to building a gaming PC. I'd rather make the investment now than have to worry about being underpowered in a year. Of course if I could get something nice for less that is also perfectly reasonable.
 
@Skytylz: I have no idea what you just said at the end there. :P

I suppose it's just an example of my complete lack of knowledge about the finer details of PC workings. If you would like to explain I would be happy to listen.

" $2,000 will get you a pretty  bad ass computer.... so go core i7 and maybe a 5870 and crossfire it someday! "

" Wow, thats alot of cash, I would definitely look around.  If you can build it yourself, it is usually cheaper.  Stores online and real will vary ALOT with their prices, so don't jump the gun.   http://www.cyberpowerpc.com/landingpages/intel/i7/ This was first link I saw with somewhat reasonable prices. GL "

I hear everyone saying building is cheaper than buying a prebuilt system, but what's the best way to get the OS (and I don't mean Linux?)

" @SeriouslyNow: Alright, I'm going to nod and agree with what you just said. It looks pretty impressive. Lord, I hate being this clueless. "