FYI there is a but with the nvidia-glx-new in Ubuntu
See here :
The bottom line is not only do you need to purge the nvidia-new-glx you also need to :
sudo apt-get remove --purge nvidia-glx-new
sudo rm /lib/linux-restricted-modules/.nvidia.new.installed
Otherwise you will get an error message :
Error: API mismatch: the NVIDIA kernel module has the version 1.0-9755, but this X module has the version 1.0-9631. Please make sure that the kernel module and all NVIDIA driver components have the same version.
*Obviously the version information varies with which driver you are installing.
*I know this information is in these forums, but I though I would add the information to this thread as well