Install instructions for Ubuntu 6.10 (Edgy Eft)

You have to make first sure that you have the right kernel running, with the right kernel headers. It seems on Ubuntu edgy that they are provided with the CD on x86 based machines, including 64 bits versions. I do not know about other architectures (such as power PC). 

You can now install the driver provided by ati.com: 
sudo apt-get update 
sudo apt-get install xorg-driver-fglrx

You might also want to install a control panel for your graphic card. Please note that I do not recommend it, as it seems to be buggy, and generally doesnt work. 
sudo apt-get install fglrx-control

Generate a new set of module dependencies so the fglrx driver starts properly. 
sudo depmod -a

After that, you have to configure xorg to use your graphic card. The aticonfig tool, provided with the driver, will do that for you: 
sudo aticonfig --initial 
sudo aticonfig --overlay-type=Xv

As ATI are well known not to be able to provide correct drivers for their hardware, you will have to deactivate the composite extension in /etc/X11/xorg.conf , otherwise you will get a jerky video display. 
sudo gedit /etc/X11/xorg.conf

add the following lines at the end of your xorg.conf 
Section "Extensions"
        Option      "Composite" "0"
EndSection

Don't forget to save. You can reload xorg by pressing Ctrl Alt and Backspace simultaneously. If you are looking for a specific video configuration please read the driver's manual. It will tell you all about dual-head configurations for example  . If you are looking for a good graphic card, please visit nvidia.com.