13.04 Nvidia

Ctrl + Alt + F2
sudo apt-get install -y build-essential linux-source linux-headers linux-headers-generic linux-headers-`uname -r`
sudo service lightdm stop
sudo apt-get remove nvidia*
sudo apt-get purge xserver-xorg-video-nouveau
chmod +x ./NVIDIA-Linux*
./NVIDIA-Linux* # run the installer twice if any errors
sudo nvidia-xconfig
sudo reboot

rm /etc/X11/xorg.conf; nvidia-xconfig may fix a black screen issue.