I've got some wierd results to report. I made sure vsync was off in both the Windows OpenGL settings and in Quake3. I closed all programs and underclocked the CPU back to 533 At first, the framerates were as follows: (All in fast 16 bit)
640x480 - 60.1
800x600 - 60.2
1024x768 - 59.8
Then, I restarted the computer and all of a sudden, the framerates dropped 20 fps across the board. So, I overclocked back to 872 and it benchmarked at follows:
648x480 - 64.1
800x600 - 64.0
1024x768 - 61.2
The fact that at 533 MHz it performed almost as well as at 872 at first is baffling to me. Then, why would it drop 20 fps just by restarting the computer? BTW, again, it's not just Quake3 that is slow. 3dMark 2000 gets only 3800 3dmarks at default settings of 1024x768 and 16 bit. Looking through the online results browser, I see people with 450 MHz Celerons getting above 4000 3dMarks at those settings, and no one getting anywhere near as low as my scores. So, whatever the problem is, it's not limited to Quake3 or OpenGL. Again, thanks for your help everyone, and as soon as I get the time, I'll probably do a total format and start from scratch on this thing.