I'm also experiencing this and I also have a GeForce 8800 GTX. I'm running on Vista 64-bit with the latest drivers. Running DirectX 10, of course. My crashes aren't as frequent, though. I get one after maybe an hour or two of playing. At one point in the big battle in the graveyard (first swamp), I tried several times to complete the castle battle with the renegade kid and it would crash everytime. At one point I got a "pure virtual call" error. I sometimes get exception errors. Sometimes it just hangs with the stutter sound.
I'm pretty sure these constant crashes were the cause of my hard drive corruption, since I still can't stop playing this game. It is a wonderful game, just not real stable on my system. I may have to give it up, if we can't get this fixed.
FWIW, I thought about disabling DEP (data execution protection) in the BIOS, but didn't. Some of the errors sound like that. Odd that there seems to be an 8800 central theme here. The last game I had that problem with was Gothic III. It also didn't like the 8800 video cards.