I have my system back to stock on CPU and GPU.
I'm using a 5850 direct CU.
I get the "driver has stopped responding and has recovered" error every so often only when playing Fallout 3.
So far it's only Fallout 3 GOTY that gives me problems. Metro 2033, Dirt 2, GRID all work fine (but I don't play them for 3 hours or more