I had to get access to my girlfriend's laptop before I could post this...
As a perfect example, my girlfriend's laptop runs Ubuntu 10.04 Beta with the nonfree nvidia driver.
So xorg has to be told to load this driver instead of the open-source one.
This is her entire xorg.conf as created by Ubuntu:
^^only put in the absolute minimum necessary to get the desired effect.
$ cat /etc/X11/xorg.conf
Identifier "Default Screen"
Identifier "Default Device"
Option "NoLogo" "True"
so for the OP, is should be maybe just a couple sparse sections with a couple modelines for 1024x768.