Jared,

> If you start Xorg with 'startx -- -logverbose 4', do you see any 
> additional information in Xorg.0.log?


Just sorry for that. I just added the hack "Options bustype PCI" and it 
works. Hadn't found the hack yet when I posted the message.
Just what bother me is that, despite a frame rate given by glxgears over 
200 fps, top says 0.0 % Idle… Strange. But it works, nevertheless.

Cheers,
Vincent