Dual boot Xp/Ubuntu on RAID disks

Hello, I'm impressed with Dells move towards Linux as a standard load on new machines. Currently I'm using a Dimension 9100 running XP but would like to switch to Ubuntu. BUT...... I have quite a bit of software that I have paid for that only runs on XP so would like to keep that as an option. Dual boot! i hear you say. great, sign me up... BUT...... I have 2 drives in a RAID array on my machine. So how do I get a second partition and run Ubuntu on it without trashing my current XP instalation? Help and advice, gladly recieved.