This is my complete /etc/X11/xorg.conf file after a fresh install of ubuntu 11.04 (graphics card: nvidia 6200):
Identifier "Default Device"
Option "NoLogo" "True"
As you can see it is almost empty. It doesn't look anything like other xorg.conf files I've seen. There is no "driver" line, for example.
I can generate an xorg.conf file by running "nvidia-settings". Then I get an xorg.conf file that looks normal. But how does the system work with an empty xorg.conf? Where is it getting the information?