Matrox G450

I have got a Pentium 2 350, with a Matrox Millenium G450, when i install Opengl, and i restart my computer, i come back in windows 98 SE it says that i have a Matrox G400 and my screen resolution is 640 x 480 with 16 colors! When i change it back to G450 and it restart, windows changes the settings back to G400! This only happens with Ogengl! What can i do about that, because now i can’t play games! Please help me!