Win 98 vs Win XP

Does anybody know why my app (VC++6, MFC) runs really nice in Win XP but really slow in Win 98 on the same PC. I’m sure I have the latest drivers on both.

What video card? I had a similar problem with my work computer. I originally had 98, and was upgraded to 2k. Unfortunately my card (Trident3d gag) only had an OpenGL ICD for 9x so now when I’m bored at work and doing OpenGL stuff, I have to suffer with horrible framerates.

GeForce 2 MX