Carbonite is good but has limitations set to only work for (if memory serves correctly) certain OS's, and will not back up external drives. It only allows cloud storage and as such could take an extended amount of time to re-download all your data. The UI is very user friendly and stores the last 30 version changes of each file.
CrashPlan looks like a great product, offering the ability to save to the cloud, as well as other computers and/or hard drives locally or remotely. I only had one issue (a question really) and was snubbed by the company for asking about storing to remotely mounted ssh filesystems by the help center and the CEO (who responded via twitter after a bad tweet about their support). So hopefully it just works for you. Its aslo cross-platform. While I may be bitter about it- its one of the best backup utilities I've seen yet. The UI is easy and allows you to set whatever number of version changes you like.
I've used both in different circumstances extensively.