Only new ATI cards can use the fglrx driver.
Big desktop on older cards with all desktop effects is not difficult though. All that is needed:
1. no fglrx driver, with
you again use the default driver, which should be ati or radeon
dpkg-reconfigure -phigh xserver-xorg
2. Unfortunately, there is a nasty bug in the ubuntu kernel with ati, so you need to downgrade or upgrade the kernel, see launchpad bug. So I got a newer kernel. Only do this as long as the launchpad bug is not fixed.
3. Now you run on the terminal xrandr to determine your outputs.
4. Now update your xorg.conf using the outputs to have a big desktop. My xorg.conf is:
Note in the above that my identifiers for xrand are VGA-0 and DVI-0, you should replace it with your idents (Specifically "Monitor-VGA-0"). Furthermore, you must set the Virtual key to the maximum big desktop you want to create. And one Monitor section must contain a RightOf, ... setting.
# xorg.conf (X.Org X Window System server configuration file)
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
# Edit this file with caution, and see the xorg.conf manual page.
# (Type "man xorg.conf" at the shell prompt.)
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# Note that some configuration settings that could be done previously
# in this file, now are automatically configured by the server and settings
# here are ignored.
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
# sudo dpkg-reconfigure -phigh xserver-xorg
Option "RightOf" "VGA"
Identifier "Configured Video Device"
Option "Monitor-VGA-0" "VGA"
Option "Monitor-DVI-0" "DVI"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
Virtual 2048 768
That is it. I have the impression for my card (ATI Technologies Inc RV515 PRO [Radeon X1300/X1550 Series]) the KDE 4.2 desktop is snappier than with fglrx under Kubuntu 8.10. But then, it could be the newer kernel.
Well, I would try it. It is an easy xorg.conf to have, and it would be shame to use fglrx if the radeon driver works just as good. Best of all is that you can do bug submissions for those drivers. And you can improve performance by taking the latest stable drivers from the swat ppa