the error is caused because the nvidia kernel is not updated (compiled for new driver). to do this, reboot your system to run level 3 so X is not started. login the terminal as su - and then:
cp -a nvidia* /etc/udev/devices
chown root.root /etc/udev/devices/nvidia*
reboot and you should be good to go. you need to have the driver installed FIRST before running what's above. after rebooting, X will load the generic 'Vesa' driver unless you have already updated /etc/X11/xorg.conf for your screen settings. if you haven't updated xorg.conf, you can look at samples of this file elsewhere in these forums.
hope this helps. nVidia is THE MOST LINUX FRIENDLY vid card manufacturer out there.