I learnt a new technique for getting my X desktop to play ball with full screen games. It's the meta mode set up. One adds a metamode list in the screen definition and X alters the way it works depending on the meta mode invoked. e.g here the TV turns off when a full screen game launches itself on the main display.
Option "metamodes" "TV: 1024x768 @1024x768, DFP: 1280x1024 +1024+0; TV: NULL, DFP: 1280x1024;
NVidia only. Helps a lot in getting games to position properly when run under cedega and using a WM like XMonad.