AMD CPUs are not as fast as the top Intels like Sandy Bridge or i7-900 series, but, they can support playing games no problem. And, websurfing and basic office tasks with ease....
CPU 955 $140
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103808
Motherboard: (I always like to plan for supporting 2 video cards as this is generally a good upgrade path should you need it.)
For NVidia cards you need a MB that says it's SLI (two GPU ready) $99
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131637
RAM: $50
I prefer G Skill, Corsair, or Crucial. DDR3 either 1333 or 1600 will do. While 4 Gb is plenty, 8Gb is a nice upgrade.
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231277
PSU: $165
I prefer Antec or Corsair. While 650watts is rock solid on any one card. And, good on a pair of lower end cards. If ya want to plan 5 years, just do the power supply right at 850watts then you can easily move it to your next build too.
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139011
This one's on sale for $127 and would be fine up to a pair of GTX 570's....
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139010
Hard Disk: $50
I prefer Western Digital. Get a Blue 500Gb or Black are a bit better. Any larger size is fine too... (just don't get a Green...) You can also get a 3Gb/s hard drive since the MB above doesn't support 6Gb/s if you can find one, might save a few dollars. But, either will do.
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136769
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136795
Video Card: $250
At this price point, the 560 Ti. Or, the slightly older and only a bit slower, 460 MSI Talon it is factory over clocked to the performance level of a GTX 470, and Only $200...with a FREE game...
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127534
DVD: $20
Buy just about any DVD drive you wish...
Case: $100 to $200
I prefer Cooler Master HAF's, Antec, and Corsair. But its a very personal taste choice... Just stay away for just about any case that's less than $100, they just cut too many corners.
Win7 64 bit Builders edition $90...
SOOOO, $875 give or take a bit
If ya have more money, just get a better video card. AND, get a CPU cooler the 212 is highly recommended..