I don't suppose you saw the If you have problems, PLEASE read this first!
Your X log file would be much more helpful than a vague report of something not working. I know, you probably don't have a clue what's not working, but your log file does know, and with that, we can hopefully figure out what's going on.
Actually, maybe that's not even important, now that I think about it. Were you by any chance booted to Mandrake's failsafe mode when you installed the drivers? If so, you should know that Mandrake's failsafe mode changes much of the system's characteristics (enough so that the nVidia installer gets all confused when it tries to configure the kernel module). You should boot to normal mode when running the installer. To get X to not load up, you can edit /etc/inittab and change the "initdefault" line (there are comments around it; you want runlevel 3), then reboot.
But there's an easier way to try to fix it, if that's the problem. Edit /etc/modules.conf, and change alias char-major-195 nvidia
to alias /dev/nvidia* nvidia
, then save and exit, and run /sbin/depmod -a
as root. Then try rebooting into non-failsafe mode.