gdm fails after 3.1r2 desktop install

[Phil Hammond <phil@hammondo.org>]

(My first attempt to install any Linux system so bear with me please!)

I did what appeared to be a clean installation of 3.1r2, but on first 
startup gdm says:

GDM: Xserver not found: /usr/X11R6/bin/X :0 -audit 0 -auth 
/var/lib/gdm/:0.Xauth -nolisten tcp vt7
Error: Command could not be executed!
Please install the X server or edit /etc/gem/gem.conf to point to the 
right place.

and then

I will disable this X server for now.
Restart GDM when it is configured correctly.

I seem not to be the only person to have this problem. The suggestion 
in a few other places has been to install x-window-system and 
x-server-common and (perhaps) x-window-system-core. But apt won't let 
me install x-window-system because it depends on a virtual (or dummy) 
package xprt-xprintorg.

Is there a way to force an installation of x-window-system even 
without xprt-xprintorg? Or is that even going in the right direction?

Thanks in advance-
PH
--