Sorry I re-read your post and saw you're running Ubuntu. Guess it pays to read first!
You can follow the steps on my blog, but instead of using the command line you'll want to open a Gnome terminal instead, and use the nano editor instead of ee. When you edit your xorg.conf file you may need to log out and back in again before you can select the new resolutions. Again my experience is with FreeBSD and Slackware not Ubuntu but other than those the steps should be the same.
Last edited: Mar 22, 2007