@Pete Did it say “Display driver has stopped responding and has recovered” ? That’s a hard one to pin down. My 8800GT was ~two and a half years old and behaving the same way as you described on games as graphically unintensive as Halo. Thought it was overheating, messed with a lot of settings and internet solutions, but nothing worked. Plugged in a friend’s extra graphics card, no problems. Replaced my card with a new one and never had the problem again.
If you know anyone who has the right kind of card laying around, try swapping them out to see if that’s the problem. If it is, hey, at least you have a mighty new PSU for a mighty new gfx card. I recommend EVGA, they’ve got a pretty good manufacturer’s warranty if you register within… 30? 90 days? of purchase.