If I remember right, the Matrox Millenium 2 only had limited 3D hardware accelleration capability. Most games didn't support the 3D features on it, and only played in software emulation mode.
If you can still find OpenGL drivers for the card, however, it should be able to play GLQuake at 640x480 with a medicore framerate. I wouldn't even bother trying to playing any 3D games newer than that, however.