http://www.newegg.com/Product/Product.aspx?Item=N82E16814161402
HiS HD 7770 - 119.99$
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161403
HiS HD 7750 - 99.99$
I am sorry ([strike]well, not really because I don't like Nvidia's expensive power hogs[/strike] some 400 series) but both of these simply demolish the new GT 640 newegg now has for the same price.
I have the same processor and it will perform flawlessly under any hardcore game with my VGA coming next week, the MSI R6850. (1440x900)