You won't find that key under Win2k, it's stored differently. I don't know how to set the refresh rates in Windows 2000.

Regarding the OpenGL/DirectX thing... I know they use OpenGL. Sometimes, though, I've heard of programs which use OpenGL for certain things, but also have to use DirectX for certain other things. I don't know enough about the subject to know exactly what things get done by which engines. It was a wild guess, I know that there is a force-refresh option in the DirectX Setup software so I thought it would be worth a try.