I've used Carbonite for a couple of years. I really like it. Takes a long time for initial backup (at least for my 60GB), but once it all got backup up it keeps up really well.
For $5, it's hard to beat it really. One feature that they added (and I think Mozy has too) is the ability to 'own' your own key. Basically so only you, and not them, have access to your data. Good for security, really bad if you lose your key
