problem with opengl on my g400

I’ve got this problem. My matrox g400 wont acelarate any opengl. I got it to run with g400idc.dll on my system directory, but as soon as I isntalled glsetup, it gone bezerk again! I get the normal error mesage when I try to run the screen savers that use opengl.
I’ve also been told that it may be DirectX 7,0a that is making the problem, but I don’t know any way to downgrade directx

PLEASE HELP MY, I cant live much longer without Quake!