I've had a run of bad luck with my laptop recently (failing motherboard, dodgy screen, etc ,etc) so I've been paying extra attention to backups.
My main backup solution is the Tivoli Storage Manager service provided at work. This runs automatically each night and backs up my work files.
However, it doesn't pick up things like my iTunes library and it wouldn't really help get me back up and running if my disk were to fail.
Therefore, I also run an intermittent full-disk copy. This means that, were my hard disk to fail, I could swap in the image and then only have a week or so of material to reapply from TSM.
I use ImageCenter for this task. I love it. It just works.
(Except for the small problem that the disk I copy to is not SATA, but my main disk is.... in other words, I have no hope of booting from the image.... I'll fix that problem next time :-) )