Wow, the new Nvidia drivers made a big, big difference in performance. I try to run things at 1920x1200 so I don't have to worry about scaling, and that was unplayable with my old drivers. The new ones gave me a ~50% boost in most places. I was getting framerates in the 20s frequently with the old drivers, and it only dipped into the 20s during the battle at the end with the new ones.
3.6GHz P4, 2GB, 320MB 8800 GTS, in case anyone cares.