Cloud-storage services take three distinct approaches: backup, folder syncing, and drop boxes. We've yet to find a single service that offers the perfect blend of all three, but you can easily combine a couple of services, and many great options are free.
Backing up the entire contents of your hard drive to the cloud comes with a trade-off. What you get is peace of mind--the knowledge that your data is safe in the event that your home vanishes into a black hole that somehow leaves the rest of the planet intact.
What you give up is speed: Even with a very fast broadband connection, can take weeks. Once the initial backup is done, however, regular daily backups of just the newly changed files take almost no time at all, and happen in the background with no effort on your part.
Restoring data can be painless and quick if you just want to recover a recent version of a particular file, but if you ever need to run a total system recovery, it could take days. Fortunately, most cloud-backup services offer the option of mailing you a recovery disc with your backed-up data on it.