Originally, I had an Ubuntu Edgy Eft installed on a HP Compaq tc1100 Tablet PC. Yesterday, I installed xfce (to get "xubuntu"), and the results were pretty good, although I'm still getting used to the menu item placements and different programs set as default for Xubuntu vs Ubuntu (e.g. Mousepad for Gedit, Thunar for Nautilus). Here's how I did it:
sudo apt-get install xubuntu-desktop
this command, typed into the terminal (which can be found under Applications --> Accessories --> Terminal in Ubuntu 6.10), automatically installs all the packages necessary for an xubuntu install, including the latest version of xfce (currently version 4.4). After rebooting (or simply login out), you can log into your new xubuntu desktop by selecting Options --> Select Session --> Use Xfce (or Gnome, if you're switching back to Ubuntu after having used Xubuntu).