And because you will by default be lazier than you should be, sit back right now and think of some worst-case scenarios that would screw up the projects you're currently working on, and write down what you need to do to avoid those. Living out the disaster scenario in your head may preempt living it out in reality.

Because right now my backup harddrive broke and my checking account is in the red, my personal lazy backup system for day-to-day important files is Dropbox: http://www.getdropbox.com/

If I'm missing an obvious free solution that doesn't require me dragging folders into Dropbox every day or two, please let me know.