Just a fyi,
Rather than booting to different runlevels, as suggested for the nvidia driver install, I am able to <ctl><alt><f1> to tty1, and do:
telinit 3
This shuts down the xwindow server. I am able to install the nvidia driver and it doesn't complain. You can then vi your XF86Config-4 and change nv to nvidia as the installer suggests. Then just do:
telinit 5
This will automagically start the xserver, and you should see a nice nividia splash, just like I do!
I've done this several (dozen?) times with no ill effects. I'm currently running Mandrake 9.1, but I am downloading Fedora FC2 test2 as I type this.
I hate to boot when I don't have to.
Comes from years of Windows software installs/resolution tweaks/any other senseless reason to reboot.
Dan