Ubuntu video card
If you really messed up xorg.conf and fail to get your backup working, you can reconfigure xorg using
sudo dpkg-reconfigure xserver-xorg
For advanced configuration run aticonfig from a console window or AMD CCC:LE from the Desktop Manager Menu If the X Server fails to load on next attempt, please run aticonfig --initial -f from the console. (Note: This will remove all device/monitor/screen sections in your X Server configuration file).