Howtoforge posted a guide about setting up Kubuntu 8.04 as Linux desktop

This tutorial shows how you can set up a Kubuntu 8.04 (Hardy Heron) desktop that is a full-fledged replacement for a Windows desktop, i.e. that has all the software that people need to do the things they do on their Windows desktops. The advantages are clear: you get a secure system without DRM restrictions that works even on old hardware, and the best thing is: all software comes free of charge. Kubuntu 8.04 is derived from Ubuntu 8.04 LTS and uses the KDE desktop instead of the GNOME desktop.

The Perfect Desktop - Kubuntu 8.04 (Hardy Heron)