It is so easy to do it is almost mac-like. Install the Restricted Drivers, then from a terminal, issue the following command:
gksudo nvidia-settings
It will pop open a GUI for the Video card. Click on the X Server Display Configuration, and select TwinView, or Separate X Screen. Select the resolution and orientration. Twinview works well, but I don’t particularly like how windows pop to the middle of two screens broken in half. I prefer to use Separate X screen.
