For those of you who are successfully installing the driver without getting errors but who have really slow performance, try setting the AGP option to use the nVidia one. By default, the drivers will try to use your distro's AGPGART.
My scores jumped from around 160 FPS to 900 FPS using glxgears. Also my CPU usage dropped in half.
Dual AMD Tyan Tiger MP
GeForce FX5200 128MB
Fedora Core 1 (original kernel etc.)
Nothing else mentioned made any difference except the above. Good luck everyone!