I need help

Okay, so I had decided to upgrade my XP partition to Vista, unfortunately, it crashed. Windows no longer works, though I must admit, I didn't think Vista would install.

Well, apparently it had gotten by me that I had accidentally strayed from the instructions on one minor minor issue. The partition format. I accidentally formatted the partition NTFS, instead of FAT. This has caused massive anger for me (none taken out on my beautiful Mac). Well, the Mac Installation CD Disk Manager refuses to delete the NTFS partition. I can no longer use that space (which is really bugging me cuz I only have 80 GB), and I want that space back for Mac OS X. I don't particularly want Windows on my computer, and the XP cd won't format it FAT.

I'm at a loss, I don't want to spend a fortune for a new hard drive (as this is perfectly good). What do I do?