Remove Vista Install

My computer RAM recently went bad - I ended up losing 3GB due to a short in the motherboard or something. Anyway I replaced everything, but could only afford 1GB at the moment. My computer was running horribly slow running vista ultimate on just 1GB (LOVED it with 3 tho)...

Anyway my Vista install became corrupt somehow in the damage and I decided to downgrade to XP till I can get the RAM back up where Vista likes it. So I re-installed XP on the same partition (pry a bad choice but I did not want to lose my WoW install and all my music and movies that I have ripped to my hard drive. The wow install alone takes over an hour and the music is countless hours of swapping discs in and out. Anyway so everything works fine, I am typing from it right now, but there is this corrupt Vista install sitting on my hard drive doing NOTHING but taking up space. Some of the files wont allow me to delete them even though they come from another OS. Anybody know how to remove something like this?