HIS H489FN1GH Radeon HD 4890 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card
-$10.00 Instant $179.99 http://www.newegg.com/Product/Product.aspx?Item=N82E168...
i decided on the 4890 over the 5850 because of the budget. possibly buying another 4890 once its price have dropped very low.
Check out my post here. It is an extreme gaming PC and only costs $1231.98 AFTER shipping/taxes.
This of course has extras which you probably already have at home that you can knock off of the price: keyboard/mouse, cd/dvd burner, Windows operating system. This will save you almost $200.00.
I have spent at least 25 hours doing research on the best compatible, future-proof system. This system is pretty much guaranteed to last at least 5 years because of its expanding capabilities and motherboard support.
For Cases look at Antec 300 illusion, Antec 900, Antec 902, Antec 1200 or the Coolermaster HAF 922 or HAF 932. All have great airflow to keep your system cool.
I have found that when living with other people, headsets are a far more useful way to go than speakers. No complaints about what you are listening to or how loud it is.
Get a wired optical mouse. Dieing or making other players wait while you change mouse batteries sucks. Even a cheap logitech will do ok, though expensive gaming mice give you more button options if you want.
If you plan to play XBOX 360 on the screen, I suggest going for a 16:9 monitor instead of a 16:10, like those 23 inches with 1920x1080 native resolution ( FULL HD ). Otherwise, it will look stretched.
PS: You will play xbox 360 2-3 feet away of your screen? Strange for a console... and awfull in splitscreen... ( The only reason I see console are great over PC ( besides some games not release on PC ) is for comfort. Laying down on a couch looking at a big TV with a lot of free space, and friends near, is way better than staying in front of a computer, confort wise )