Ubuntu on top of XP Pro?

Hi,

anyone have a clear "how-to" on installing the newest Ubuntu on a system that's already running XP Pro. Need to have a multi-boot system but have no clue as to how it's done!

Thanks in advance!

/Petri, U-bunt-enthusiast from Finlandia!

PS. Only have UB media on HD from download, do not have CD/DVD burning capab...