People who don't spend much time with computers imagine a clean, glass-enclosed room with a lot of people wearing lab coats and surgical masks scurrying about making sure vast reams of data are secure. In fact, studies show computer storage media are generally the least reliable storage method you can choose. I have four computers at the moment, tied together in a network. When I am working on an important project, a situation in which new files are being created and there are not many backup copies, I regularly run a backup program I designed. Not only should you back up regularly, you should also review the contents of your files regularly to be sure they are what they appear to be.
Diskettes are no longer practical for hard drive backup .
As drives get larger, the probability that you will successfully write and then read all those diskettes becomes smaller and smaller. Get a tape drive or a removable-media hard drive as a backup device. Visit my HTML tutorial These Pages Created and Maintained using Arachnophilia.