I'd stick with something in this model.
Asus P5Q-P, or Pro. ~$130
E8800/2200 ~80/140.
E2220's OC to around 3.2GHz, the 8800 to 4.4 with better cooling.
And of course, 8800GT can support most shit you throw at it, virtually everything unless you want crysis AA @ 4x.. which is insane, but you...