In Ubuntu/Kubuntu 9.04 I like to have Ctrl-Alt-Backspace enabled to restart X server, which I found a quicker way to log off and log on since I use to hop around from Kubuntu to Ubuntu and back. More here
And I want it too in my Ubuntu 9.10. Fortunately in Ubuntu 9.10 the method is easier, way easier. No editing necessary like in 9.04.