Alright, so whenever I play Fallout 3 or CoD: WaW (or any other game), the game runs fine for a while, often for a few hours.
Eventually though, the game freezes for a minute, and then I get thrown back to the desktop and get a message that a display driver has stopped responding.
I just updated to the latest drivers today, and I'm still experiencing the exact same problem.
According to the nvidia monitor, the GTX 285's temperature is at around 73C, so the card doesn't seem to be overheating.
I have a very simular system using a EVGA GTX 285 and my system used to crash like that too. I was using Vista Premium 64 bit. I switched to the new Windows 7 RC 32 bit and now I have no problems whatsoever.
I think your problem may be in the 64 bit OS.