AMD Athlon II X3 440 - $75 US
ASUS M4A77D AM3/AM2+/AM2 AMD 770 ATX AMD Motherboard - $80
This will allow you to play games like Assassin Creed2, BFBC 2 on moderate/low graphics quality. BFBC2 will benefit more with the 3rd core gaming wise. I'm not sure about AC2 for the PC (I played it on the PS3... couldn't wait for the PC release )
I hope these combos are what you might be looking for.
As for your last post gupi I would try to really stick with a dedicated card instead of going intergrated, but if you want to go intergrated go with my first combo I link above^ with a ATI HD4200 HDMI built in.