Is there a way to set screen resolution in gdm?

[Chris G]

The subject says it all really.  I'm running xubuntu 8.10 with an
Intel G31 based motherboard, thus X is 'auto configured' and there's
nothing at all in xorg.conf.

How can I set the resolution for the gdm login screens etc. so that it
matches what I use in X?  At present it switches resolutions back and
forth when moving from login to X and back.  More to the point it does
it wrong sometimes and crashes.

-- 
Chris Green