raid dual boot

I have never used Linux before. I have here an install disc for Ubuntu. I would like to install it on my PC and dual boot between Linux and the current OS, Windows XP Home. Windows is installed and run off of my RAID 0 array which consists of two SATA drives. I have also have a 160gb IDE drive on this PC. I would like to install Ubuntu on a small partition (20gb?) of this IDE drive, and leave the remainder (140gb) for backing up files from the RAID array and other PCs around the house.

I have never partitioned my drives before, and I'm not quite sure of the file systems, either. (FAT 32? NTFS?)
Any help on this partitioning and dual-booting would be helpful. Links to resources, or the straight answer. I'm looking to learn Linux for breadth of knowledge, so I am willing to do a little research into it. I just figured this would be a good place to start.

Thanks for any help!