RedHat appears to have support in the Phoebe beta 2.4.20 kernel. I may install that kernel, or I may wait until the final version shows up and try that. Compiling my own custom kernel is a pain. It's bad enough I have to custom compile cipe. :-(
The 4191 drivers seems to have support via NvAGP, but I'm getting some weird halting when I move windows or windows need to be redrawn. The halting appears to be in the kernel as xmms momentarily (less than a second) stops playing.
When I move windows, it gets very jerky if I move them quickly.
When I flip desktops, there is sometimes a noticeable pause until everything suddenly redraws, and during this pause, xmms sometimes stops playing.
All other UI operations are very snappy, including scrolling in Mozilla. Also, I sometimes get normal behavior for a short time after I stop playing Quake 3, or other heavy GL game.