OS on one partition Users on another

[dnanian]

Just make enough volumes/partitions on your destination drive to map 1:1 with your sources. So, if there are three partitions on your PowerBook, you'll have three partitions on the drive, and schedule three backups, one for each source, backing up to its corresponding destination.

Note, though, that a Sandbox will accomplish your goals with *two* partitions, one small (and you don't have to back it up, either, in general). Works quite well: see the User's Guide for a full explanation.