XP defaults to having a 60Hz refresh rate while you are playing Opengl and D3D games. You also apparently have vsync enabled.
Vsync won't allow your frame rate to go above that 60Hz for it is matching it.
Go to your display properties, settings, advanced, Geforce 2 tab,
opengl then turn off vsync.
In order to turn off vsync in D3D you have to install coolbits, to access vsync on the second tab of D3D settings.