Free CDs: https://shipit.ubuntu.com/
On 1st June 2006 the Ubuntu Community released versions 6.06 LTS of Ubuntu, Kubuntu, Edubuntu & Xubuntu. All these the are Long Term Support or LTS meaning they will be supported for atleast 3 years for desktop (upto 1 June 2009) and 5 years for the server (upto 1 June 2011).
Xubuntu is a derivative of Ubuntu based on Xfce Desktop environment, making it lighter than Ubuntu/Kubuntu. Escpecially useful for old or low-end machines.
Download: http://cdimage.ubuntu.com/xubuntu/releases/dapper/release/ />
Free CDs: Not Available.
So go get them!!!