As one form of back-up I highly recommend Dropbox. I use it all the time - you forget it is there and yet - files backed up constantly. Plus it has a version system in case you save over a file or accidentally delete you can just re-download. Be sure to have a local back-up too of course

Always have your stuff when you need it with Dropbox. A 2GB account is free but if you sign up using this link both you and I will get an extra 250mb of storage for free!