Beware of Mozy.
I backed up 30GB of data on my E drive. I installed a new DVD drive which windows allocated "E". Mozy then couldn't see all the data on "E" and decided to sync it ... ie all my backed up data disappeared. When I allocated E back to my hard drive Mpzy started backing up the 30GB ... from scratch.
I suspect Mozy might have been able to sort it but I don't expect this sort of issue with something I am meant to trust with my data. Bridge burnt.
I wrote about my negative experiences with Carbonite and Mozy here.
I was actually willing to pay for a solution but they both messed up.
I'm sure they are fine if you've got a small collection of knitting patterns or letters ... but anything over a few GB that you can't stick on a disc as well .. forget about it.