d3d runs funny

[FlymanX]

I have an athlon 1.33 ghz computer with a leadtek geforce 3 video card. most of my opengl games run great. also, my 3dmark 2001 scores are around the 6000 range. my problem is that many of my games that run on direct 3d are really choppy. games like max payne, undying, and deus ex run like crap in d3d mode. it's really strange since i can get such high 3dmark 2001 scores, but still get such crappy performance in d3d games. what is wrong??