Most of the data on the iBook is also somewhere else: .Mac (our mail, my addresses/calendar), a backup I made a few months ago, O's iPod (which has the music she just bought), and Flickr (which has a few pictures I didn't copy to the other machine). What's missing: a few of my purchases from iTMS and eMusic, and that's pretty much it.
I'll probably just pop a new hard drive in the iBook, and upgrade to Mac OS 10.4, which has a better version of rsync for doing your own backups. (The Backup program for .Mac users is OK, and in fact I used it on the iBook for my settings etc., but I find it rather disappointing that you can't seem to back up all users' files with it. Every user of Backup has to be a paying .Mac member, apparently.)
On the upside, I went out after shoveling tonight and got FREE BREAD at Trader Joe's. So the evening wasn't a total loss.