For years I have recommend Carbonite for backup. Once installed, it does a great job of keeping all your important data (pictures, files, music) backed up safely in the cloud. With it, a computer crash becomes more of an inconvenience and less of a disaster. Fix the computer or replace the computer, reinstall Carbonite, download all your files. DONE.
So why have I started to recommend iDrive as an alternative?
Overall it does the same thing, but the pricing models are VERY different.
Carbonite will backup UNLIMITED amount of data for ONE computer.
iDrive allows you to purchase a certain amount of space and backup as many computers as you need until you fill that space.
Have one computer? Go with Carbonite. Need to back up many? Go with iDrive.
Whatever you choose, backup! You critically need to.