[dnanian]

OK! Don't let any of the more technical discussions here in the forum fool you: this stuff is easy to do. So, relax. Really!

In general, I strongly recommend that you isolate each volume's backup in its own volume, by partitioning your backup drive appropriately. That will make it MUCH easier to restore, and -- on top of that -- you won't accidentally make a mistake during your backups and erase data you wanted to keep, or overwrite files, or whatever. (Combining volumes is just not a good idea. Too easy to make mistakes, and harder to restore from, too.)

Partitioning is easy, and can be done with Disk Utility. Just start it, choose the backup drive, and then choose "2 partitions" -- or the number of partitions you want. More than likely, you'll want three: one for the PB backup (the 80GB drive), one for the ProTools rig (200GB), and the remainder for regular storage.

The sizes of the partitions should be the maximum size you anticipate taking up on the drive. So, if you don't think you'll ever get to 80GB, use the maximum you think you'll need. Remember, though, drive space is cheap, and we all fill our drives, so it might be best to make an 80GB, a 200GB and a 20GB partition.

Once that's done, target your backups appropriately to the right partition, and you're all set.

Make sense?