Here's an interesting limitation to relying on OS X's Migration Assistant as back-up security.
A colleague of mine has an iMac and an iBook, both pretty much in sync.
For various reasons, the iMac got into all sorts of problems, so he did a clean install using the factory disks -- 10.4.10 -- assuming he could then use the migration assistant to restore everything from the iBook.
Problem is that the iBook is running 10.4.11 and Mig Asst baulked at restoring from a newer system.
This is interesting because, when you first turn on a new Mac, or start afresh with a clean install, the Setup Asst asks if you have an "older Mac".
So, the "Target Mode" Mac is older, but the system on it isn't.
A trap for young players and one I haven't seen before.

mct

That's probably to be expected - you can't migrate data from a system that is newer than yourself, since you don't know how it works! (I'm not actually a computer, btw)

You know that you can run Migration Assistant later on, right? So you can do all the software updates on the iMac, then open Migration Assistant from the Utilities folder?

forgie

That's what I expected and recommended.
Just a word of warning for those who may rely on Mig Asst to act as a backup -- then, after reinstalling the original system on the stuffed machine, find that the "good" machine is running a later version.

mct