I decided to try LXDE on my Samsung NC10 - I've installed the Gnome Power Manager and I've got it starting on bootup. The Brightness Up/Down buttons even work with no further work!
What I don't seem to be able to do is to get the processor speed down when running on the battery. It runs at the same speed on mains and battery and the cpufreq applet reports that it's in "Performance" mode. Does anyone know what I need to add or to do?