Comment 3 for bug 250792

Ok, I've redone a fresh install of Xubuntu Hardy 8.04.1.

Then I ran
- apt-get update
- apt-get upgrade (it downloaded a update of restricted-modules)
- apt-get install mesa-utils

Reboot (just for purity)

Then:
- Applications > System > Hardware Drivers, I enabled ATI accelerated graphics driver (it downloaded something).
- then reboot

I'm now running the ATI drivers:

:~$ dpkg --list | grep restricted
ii linux-restricted-modules-2.6.24-19-generic 2.6.24.13-19.45 Non-free Linux 2.6.24 modules on x86/x86_64
ii linux-restricted-modules-common 2.6.24.13-19.45 Non-free Linux 2.6.24 modules helper script
ii linux-restricted-modules-generic 2.6.24.19.21 Restricted Linux modules for generic kernels

My xorg.conf contains:

Section "Device"
        Identifier "Configured Video Device"
        Driver "fglrx"
EndSection

~$ lspci | grep VGA
01:05.0 VGA compatible controller: ATI Technologies Inc RS690 [Radeon X1200 Series]

After all, I still get "SGI" as client glx vendor string.

If you have any more questions, let me know.