After about a million forum posts, I've finally got it worked out. Hopefully someone will find this useful.
ATI don't provide downloads for XFree86 4.3 drivers for their Radeon R200 (9200) & R300 (9500/9700) cards on their website. However, there are some out there, released by a European branch of ATI for the FireGL series of workstation cards, built on the same core.
Yes, until very recently, the AGP support for the NForce2 chipset, and presumably the NForce1, was broken. No AGP8x for you, and probably lots of errors starting up.
Well, you need a few things:
Install the RPM. Uncompress the .tar.gz into /lib/modules/fglrx (so the files are in /lib/modules/fglrx/build_mod/). Build a module for your kernel.
Now run fglrxconfig and create a configuration file. Copy all the other stuff that redhat-xfree86-config does so much nicer, and you're away laughing. Hopefully.
fgl_glxgears doesn't run on my machine (error: Error: couldn't get fbconfig) and I've love to know why. -- CraigBox
I finally managed to get this to work: the error 'Error: couldn't get fbconfig' occurs if the GL-libraries are incorrectl. The ATI proprietary driver overwrites the file /usr/X11R6/lib/libGL.so.1.2, so this is the library that should be used, and not mesa- or nvidia-versions of it. All libGL.so* files should link to this. You can check the library dependencies with 'ldd': for example 'ldd /usr/X11R6/bin/fgl_glxgears' gives the libraries used in fgl_glxgears. Check this. It works for me now. Feel free to correct me if I'm wrong. -- !MathijsRomans?