I recently bought a LaCie 500 Gb Fireware drive for use with my TiBook. Then I bought a copy of Synchronize Pro. Synchronize Pro can be set to start up automatically whenever the drive becomes available. That way, every morning when I plug my laptop into the Firewire hub, the back-up kicks off automatically. One of the things I did was partition it so that I had a partition about the same size as the hard drive on my laptop (60Gb in this case). I have Synchronize Pro to mirror my laptop harddrive to the partition as a bootable system back-up. Of course, I checked it to made sure I could really boot from it.