I have the stutter graphics problem too... with a 3.16 core2duo and a 8800GT 256bit 1gb ram, and 4gb system ram
doesn't matter if I run it in 800x600 or 1680x1050 it's still the same... sigh. finnished the game, but it sucks.
btw stuttering graphics only occur on the outside usually. lowered the distance to draw geometric stuff, still the same...