O.K. I manage to install Ubuntu 8.10 and the ATI Readon HD 2400 pro PCI-E driver yesterday and it worked because I have compiz installed but after I updated my system with all the package updates, I restarted my system and my ATI Driver was disabled! I try to enable it from the Hardware drivers with it doesn't work activate anymore :'( it just says downloading 0% then the window closes.
oh and I tried "glxgears" and this is what it gave me
psplegendpro@psplegendpro-desktop:~$ glxgears
X Error of failed request: BadRequest (invalid request code or no such operation)
Major opcode of failed request: 159 (GLX)
Minor opcode of failed request: 19 (X_GLXQueryServerString)
Serial number of failed request: 10
Current serial number in output stream: 10
psplegendpro@psplegendpro-desktop:~$
I'm not sure maybe a bad package update?