The xorg.conf files on that site are garbage. The one you have downloaded is a prime example. I would advise you not to use them.
The above xorg.conf uses the fbdev driver - a generic unaccelerated driver. You should only use it as a last resort.
Have you tried turning off KMS? - http://ubuntuforums.org/showthread.php?t=2053596
The xorg.conf files on that site are garbage. The one you have downloaded is a prime example. I would advise you not to use them.
The above xorg.conf uses the fbdev driver - a generic unaccelerated driver. You should only use it as a last resort.
Have you tried turning off KMS? - http:// ubuntuforums. org/showthread. php?t=2053596