Most current Linux distributions made it very easy to configure your graphical user interface, aka X Window System. However, the graphical tool to configure xorg.conf, the X11 config file, is not always perfect. Personally, I find it easier to edit it manually, i.e., using vi or any other text editor. It was a hit or miss exercise for me before but with this tutorial, it makes manual editing super easy. Try adding another monitor or two on your desktop system and you'd be surprised how manual editing rocks. :D