At ninja-assassins.com they have written a detailed report about migrating your desktop from Windows to Kubuntu.
Read the lengthy article
After a few weeks, my desktop is running great (screenshot on the right) and I haven't booted into Windows XP at all since I started the migration. This is partly due to the fact that I have my essential applications working, and partly due to the fact that I'm using an Apple USB keyboard and I can't seem to select a different operating system in Grub or Lilo with it.. I currently have a ps2 keyboard attached just to select different options. I think I need to upgrade my PC to a newer motherboard as the old one is a getting a bit flaky and slow (no onboard USB-2 for example).