[rodalpho]

Actually, no. Those instructions are wildly inadequate. Steps are:

1) deactivate ubuntu's version of the proprietary nvidia 170.x drivers under system|administration|hardware drivers
2) sudo nvidia-uninstall (This step can possibly be skipped; I needed it as I skipped step 1 my first try. Step1 is definitely mandatory.)
3) from a shell prompt (ssh into your box or go to a VT from the console via ctrl-alt-F2), run
sudo /etc/init.d/gdm stop
to kill X
4) from that same shell prompt,
sudo sh nvidiawhatever.run
to install the new drivers
5) sudo shutdown -r now
to reboot

(feel free to put this in the wiki, if you want)