Quake III engine, Opengl, Windows XP

The title basically sums up my problem. I had 3 Q3 engine games installed on my XP system; all ran perfectly until one day… All three caught the same “illness,” when I start the games the sound is ok but the video is VEEERRRYYY slow and choppy. Even in the start menu. I haven’t even tried to play since it takes me about 5 minutes to move the mouse to the QUIT button to kill the damned thing. I think I narrowed the problem down to the OPENGL32.DLL file which somehow was updated during some driver update or game install. I’ve lost track. I tried one fix which only managed to get Quake III Arena to work normally. This was done by renaming the file c:\windows\appatch\acxtrnal.dll to opengl32.dll and copying it to c:\windows\system32 (overwriting the old opengl32.dll). However, with this file MOHAA won’t load at all. I’ve tried deleting the all the opengl32.dll files on my harddisk but they’re apparently immortal and just keep respawning! Ofcourse, I reinstalled the video drivers (Nvidia) many times. One other thing to note: all other non-opengl games work FINE.

My system is:
512MB ram
GF2 MX 400 32mb
Dual P3 666

Any suggestions?