Open GL Nightmare

I have a P3 Coppermine 1Ghz with 256 meg SDRam and all the standard bits and pieces, 40 speed burner and a LG DVD Rom, I am having a problem with my SIS (Silicon Industries) 630/730 onboard Video Chipset, in the Bios I have allocated 32 meg ram for the video. Now the problem is when I play any game that needs Open GL Like Soldier of Fortune and Quake III Team arena, the console comes up and goes through the motions then when the resolution changes to 800x600 it comes up with an error message “This program has performed an illegal operation” and all that jazz, then the screen stays in 800x600 resolution and that’s it, now all these games require Open GL to play, I have the latest drivers, please can someone help me out