If you get the error “Failed to parse existing X config file ‘/etc/X11/xorg.conf’!” while trying to save your settings to the x configuration file, don’t panic heres a solution 
Open up terminal
First off we need to create a backup of your currently working xorg.conf file.
Type: sudo mv /etc/X11/xorg.conf /etc/X11/xorg.conf.bak
Now we need to run the Nvidia utility to generate a new xorg.conf file that the utility can actually read.
Type: sudo nvidia-xconfig
For the last step we need to run the graphical Nvidia tool as root, so you can actually save your changes.
Type: sudo nvidia-settings
Tested On ubuntu 9.10 (Karmic) - if you are using a version previous to this please do so at your own risk.