Voodoo3 OpenGL problems

I recently formatted my hard disk and then installed the latest Voodoo3 drivers. However, now it seems as if OpenGL has somehow ceased to work. When I try to run Diablo II and Baldur’s Gate II in OpenGL mode, it’s actually slower and uglier than in software and Oni won’t work at all. I only have this problem with OpenGL-only games; Unreal Tournament and Quake3 which support Glide work fine.
Weird thing is that I was able to use OpenGL before I formatted the hard disk, so it’s gotta be some driver problem.