Here's my PC specs:

GEForce 8800 GT
Intel Core 2 Duo 3.0
4 Gigs of RAM
Vista 64bit

I turned the Vsync on in the Nvidia control panel, as someone mentioned, and I managed to get through the mutant hideout with a minimum of stutter. I then walked outside to the Wasteland, and the game stops every time I move the mouse half an inch. I tried looking through the forum, but I didn't really find anything. I'm not a computer tech guy, so I don't know how to edit config files. Help would be greatly appreciated.

im running a ati6970. i was having studdering issue as well. I set the game priority to "real time" in the task manager, and it stopped completely

That made the problem ten times worse. Now it's freezing in the menus.

Ahhh, but setting it to High Priority, that fixed it. Thanks!