n00bs on Ubuntu posted a guide about installing Xfce on Ubuntu 10.10 Maverick Meerkat

Xfce is the default desktop enviornment for Xubuntu and just like KDE (from Kubuntu) it can be installed from the Synaptic Package Manager or using a Terminal command line. I will show you how to install Xfce using the command line in a Terminal window. Xfce is a lightweight desktop environment for unix-like operating systems.

  Install Xfce And Xfce Goodies On Ubuntu 10.10 Maverick Meerkat