If you know me you'll know that sometimes my computer and I don't get along...I have become an expert at backing up my computer as it had a nasty tendency to crash all the time on me! I have since replaced that computer with a new one last month.
I keep CDs, flash drives, an external hard drive, and a Mozy account back up...just to cover all of my bases.
If you don't back up you need to start right now!!