Windows 7: dual screen with 7 64 bit problems?

I have windows 7 64bit and have a problem of my games freezing about ten to fifteen minutes into gaming. both screens flicker for a second and then the game freezes. I have to alt tab or bring up task manager and then go back to the game in order for it to unfreeze but it will do it again in about 10 to 15 minutes and I have to alt tab or bring up task manager again. it happens with all games too. Arkham asylum, Borderlands, TF2, alien swarm, GTA4, prototype. I don't really do anything too hard on the other monitor but run a couple gadgets and winamp. It's happened since I upgraded to 7, and it happens with every version of nvidia's drivers I can find.

i have noticed your using a 450W PSU that may cause probs with multi screen and gaming on a 9800GTX+/GTS250 card and with the Q6600 its worse you might be hitting the limit for a GTX gamign card and a quad core id use a 550W+ PSU the Antec 750W and the Corsair is a good one there 80+ rating