If you've installed Ubuntu 10.10 and don't like to install Xubuntu (official Xfce desktop of Ubuntu) but still would like to keep Xfce as an alternative desktop, then you can easily install Xfce 4.8 in Ubuntu by giving the below command.
sudo add-apt-repository ppa:koshi/xfce-4.8
sudo apt-get update
sudo apt-get install xubuntu-desktop
|Hi, I'm the Xfce mouse :)|
Once installed, reboot your PC and when you're greeted with the login window, you should see Xfce as a "desktop" choice in the GDM log-in manager.