External Harddrive


I'm going to college soon and I have a iBook G4 and a home built PC i'm taking with me. I want to buy an external harddrive to use to back up both machines. Is there a external harddrive I can partition to do this or is it easier to get a seperate external for each?
If you get a drive for both, format it to FAT32. My Mac can read from NTFS drives but it can't write to them.

Btw, in some cases it's cheaper to buy a hard disk and put it in an enclosure than it is to buy an external disk.