1) You must blacklist nouveau:
sudo touch /etc/modprobe.d/disable-nouveau.conf
sudo gedit /etc/modprobe.d/disable-nouveau.conf
Add the following two lines, save then close:
blacklist nouveau
options nouveau modeset=0
2) Restart Ubuntu into recovery mode. See the NOTE on the bottom.
3) Boot to a different run level: sudo init 3
4) Stop X: sudo services lightdm stop
5) Manually edit the xorg configuration file. If it doesn't exist, skip this step:
use locate xorg.conf
to check.
Remove the line:
Driver "nv"
(or Driver "vesa")
(or Driver "fbdev")
and replace it with the line:
Driver "nvidia"
Remove the following lines:
Load "dri"
Load "GLCore"
In the Module section of the file, add the line (if it does not already exist):
Load "glx"
6) cd
to the driver file and then install the driver: sudo sh NVIDIA-Linux-<version>.run
Make it an executable first if necessary: chmod +x NVIDIA-Linux-<version>.run
7) If you did not have an xorg.conf file to edit earlier, let the installer create a configuration file for you when it asks.
8) Startup X and restart Ubuntu: sudo services lightdm start
The steps above are what I have used and got it running successfully. You should see an NVIDIA logo on startup, just after the Ubuntu one.
Source: http://us.download.nvidia.com/XFree86/Linux-x86/290.10/README/index.html