I gamed for a little while on my 3770K, and I got playable frames on a lot of games. Not Crysis, obviously, but Portal, Borderlands, Left 4 Dead - all played nicely.
The new APUs from AMD would be even better, and I think it's a good option.
+1 for Sheroo.
On the other hand, I see you considering a 680, so I guess onboard solution are out of the question completely. No matter what you choose, this should be great.