I am having the same issue, I have a fresh install of Mint 14, followed the same commands from above:
sudo apt-add-repository ppa:ubuntu-x-swat/x-updates
sudo apt-get update
sudo apt-get install nvidia-current
and went to text teminal (CTRL+ALT+F1)
Sudo killall mdm (end x server)
and now have the broken gnome looking, at 640x480 resolution (locked in the GUI), covering a square 3/5ths the size of my screen, centered.
in text only mode the full screen can be used.
My graphics card is GTX660M, Intel i7 processor.