I'm an Xbox-Linux noob too. I just got Gentoo (Home Edition) and it works good. It comes with KDE preinstalled. I'm not sure about the other ones, but you just install Gentoo to the E directory on the Xbox. It doesn't format anything. You just boot it from Evox and everything else works fine too. You also don't have to flash the bios to use Gentoo, not sure about the others.