The desktop CD allows you to try Kubuntu without changing your computer at all, and at your option to install it permanently later. This type of CD is what most people will want to use. You will need at least 192MB of RAM to install from this CD.
NOTE: This is an alpha (pre-) release. Pre-release version of Feisty are NOT encouraged for anyone needing a stable system or for anyone who is not comfortable running into occasional, even frequent, breakage. Pre-release versions of Feisty ARE recommended for Kubuntu developers and those who want to help in testing, reporting, and fixing bugs.