Seems there are many software choices to backing up, as well as what to back up and what to back up to. Let's take a look at some of the information.
Joe kissell has some very good information.
You can hear Joe kissell take about backups from this mp3.
Also from Dr. Mac
One mans obsession with Backing up.
And from a number of folks on Dpreview mac forums; mentioned superduper. I myself use this software and find it quite nice. I am still learning, so I don't consider myself an expert. Leopard will have time machine in the next major update to OSX.
A new one, with a twist; and it's free
Another free app, is backuplist.
ibackup is free to.
Carbon copy is shareware $5
Chronosync is shareware $30
SuperDuper is shareware $28
Purmac, a number of software choices to choose from. JonL
Pure-mac backup software
Found another site on reviewing backup software: A bit dated
Mac backup software harmful