Where does gnome keep display resolution

[Robert Moskowitz <rgm htt-consult com>]

This is on Centos 5.2, Gnome 2.16.0

/etc/X11/xorg.conf does not have any display resolution values, yet

In System > Administration > Display

There I have set Monitor type to LCD Panel 1024x768 and settings tab 
shows 1024x768.  Where is this information stored?

In System > Preferences > Screen Resolution

There is a different selection of resolution values.  Where is this 
information stored?

I am having problems on one system that is using OpenChrome.  I can set 
the Monitor type to 1024x768 and get this for the external display but 
not internal.  I go and edit the xorg.conf file, and then I only get 
800x600 resolution.  So I am trying to learn where all the information 
is kept to figure out what is getting stepped on....

Thank you.