I believe the Eee PC runs a dumbed down version of Xandros and if you need
to re-install it you have to press F9 on boot which will re-install the base
system. There are also programs available on some of the Eee PC help sites
which are supposed to allow you to install the full Xandros system rather
than the default version. The system also comes with a CD/DVD with all the
drivers for Win XP if you choose to install that OS. You could ofcourse
install Ubuntu from an external optical drive.
They even had a look at the Eee PC on the BBC2 weekend cookery programme
'something for the weekend' where they played with the voice control and the
built in camera.