This is a subject I have written on before, but I see the need to talk about it again. Backup your data! What is a backup? Why should I do it? How can I do it? I will answer those three questions here.
What is a backup?
A backup is a simply a copy of your important files. This backup or copy of your files should be located on some type of removable device.
Why should I do it?
Imagine all the things you do on your computer. You may track your checking account with Quicken. You may have centuries of genealogy data and decades of photographs. You may even have hundreds of dollars woth of music you have downloaded from an online store. Now imagine your computer's hard drive goes bad. That's not far fetched. Your hard drive is the most likely component to fail in your computer. It is also the most critical because it holds all your files. Once it goes bad, if you are lucky, you can pay hundreds of dollars to have your data recovered. In many cases, that data is just gone. If you had a recent backup or copy of all those files, then a bad hard drive would simply be an inconvenience instead of a disaster.
How can I do it?
This is not that complicated. You can buy an external hard drive that plugs into your computer via a USB cable. It will show up in Windows as another hard drive. Usually, these external drives will come with backup software that you can use to schedule nightly backups or copies of your important files. There are also free utilies available. Karen's Replicator is a good one that you can download from http://www.karenware.com. As long as the software will allow you to schedule automatic backups, it should be fine. When you go to setup these backups, just choose to backup your entire hard drive so you are sure to get any files you may ever need. I have seen users backing up just the My Documents folder, but that does not include your email files, Quicken files and many other important data files.
Now that you know what, why and how... just do it. The sooner, the better. I can't tell you how many times I have heard someone say "I was thinking about setting up backups" or "I was going to do that next week" right after I have told them that all of their kid's digital photos are gone forever.