I don't do full backups, ever.... All my important data is hotsynced to my PowerBook, and I keep copies of all the files I install on it, in case I ever do have to do a hard reset.
I really should get in the habit of doing backups of my Powerbook, though...
(Edit: After some consideration, I'm beginning to work on getting some backup software working... =) RFBackup on my Clie, iBackup for my Powerbook...)