IF you really want to remove the nVidia drivers (NOT needed, btw)...
Download (google is your friend) Kext Utility, and after the following has been removed via terminal, run it and reboot.
enable (if not already enabled) root user
open terminal, type su -
login as root
cd to /System/Library/Extensions
remove the following kexts via rm -r (if present on your system) Note: BE EFFING CAREFUL ABOUT USING rm -r ON YOUR SYSTEM. Typing rm -r * and being for some retarded reason, say, in the root directory of your hard drive will immediately and unconditionally wipe the entire drive. Boom. Gone. Forever. So use with caution. Anyway, use rm -r to delete the following files, as I mentioned:
CUDA.kext
GeForce.kext
GeForce7xxxGLDriver.bundle
GeForceGA.plugin
GeForceGLDriver.bundle
GeForceVADriver.bundle
NVDANV40Hal.kext
NVDANV50Hal.kext
NVDAResman.kext
NVSMU.kext
find the Preference Pane you want to delete (easy enough to just right-click in the Preferences panel and choose "remove from xxx") in /System/Library/PreferencePanes and delete it via the same method as above. ditto for any .plist files. If you need to manually scroll through your .plist files on your machine (there are a LOT of them... I have exactly 35,107 .plist files on my Mac), type this at the command line:
find / -name *.plist -print > /plist.txt
If you aren't comfortable in the command line, you can open up your hard drive in the Finder and there will now be a text file called plist.txt in the root directory. Open it up or search within this file for anything with nVidia or Cuda etc in the name... use your head. If it isn't insanely obvious that it isn't needed, LEAVE IT. Or don't. This file will contain the paths / file names of all the plist files on your system... once you identify one you want to delete... go back to the terminal, cd as laid out in the path of the plist.txt file, and delete the "offending" nVidia .plist file. I'd recommend an editor like BBEDIT if you don't have it if you are going to go this route... you can search for all lines containing a specific word, for instance, and then more easily see where the bits and pieces are tucked away. Do pay for it, though, if you end up using it... we need good Mac software designers. This same functionality can be done via command line, though, pretty easily if you are comfortable (i.e., grep <your search string goes here> /plist.txt)
don't log out of terminal yet, btw... simply run the Kext Utility program you googled earlier, once it has finished rebuilding all your kexts/caches, go back to your terminal window, and simply type:
reboot
As long as you didn't fubar your machine, all things nVidia should pretty much be gone.
Hope that helped. Or scared you into not touching your system... lol.
R.