But they aren't simply to use or configure.
I have played to Descent and Quake III, in my system.
Pentium II-350, 512 MB ram, TNT2 M64, SBlive!
Quake and Descent, or TuxRacer works, but I don't think more than 25 fps, but is played decently
Mplayer works well, with "xv" driver, not "x11" or "SDL"
in 640x480 run at 60% of CPU ( with ffmpeg libs )
I can play mp3, run mplayer and chat (irc)
I compile my own kernel
With this options
MTRR ( Memory Type Range Register, Mplayer use it )
but this NO
Dri, or AGP
I use Nvidia's internal AGP
I have read Nvidia's Readme