EVGA 01G-P3-1561-KR GeForce GTX 560 Ti FPB (Fermi) 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready SLI Support Video Card
$229.99 and a $20 rebate makes it $209.99 and free shipping.http://www.newegg.com/Product/Product.aspx?Item=N82E16814130623
Your new obsession will drive you broke or for a better term computer poor.
This card will give you quite a boost in performance and it will work with your 500w psu. I know you have gone with AMD as your cpu and motherboard choice but if gameing is your main use for this computer then you will be better off with Intel's Sandy Bridge and while it's too late to change now in the future you should look at Ivy Bridge and make a change latter on.