One desktop only on a multihead system?

[Roe Peterson <roe liveglobalbid com>]

Sorry if it's come up before, but I've searched everywhere I can
find.

I've got a system with twin monitors, running FC5 and Gnome 2.14.

Unlike most other users, I _don't_ want gnome to start a desktop on
my second monitor - I have an app that runs fullscreen on the secondary
monitor.

I have tried everything I can think of to make gnome ignore the second
monitor, with no success:
   - run xinit manually, and manually start gnome-session with:
         DISPLAY=:0.0
         gnome-session --display=:0.0
         gnome-session --screen=0

without success.  The desktop session _always_ grabs my second monitor.

So, before I start digging into source code, can anyone offer a 
semi-desperate
newbie some advice?

Thanks in advance.