Method 3: The Spare-PC Backup
These days it's not uncommon to own two or more PCs, and if you have family members under the same roof, they probably have their own machines as well. Why not create a "backup network" that leverages everyone's hard drives? All you need is SyncToy 2.0, one of Microsoft's free PowerToy utilities. With it, you can create "folder pairs" between PCs, copying files between them with a single click. This is a great way to sync, say, disparate photo libraries between your PC and your spouse's, and to create a backup of both in the process.
If your PCs aren't on the same network--one is at home and another is at work, for instance--try Microsoft's Windows Live FolderShare, which syncs files across the Internet (and does so automatically; SyncToy requires you to manually resync whenever you change or add files).
Method 4: The Document Backup
If you're a Google Docs user, you know that this Web-based office suite can import documents from Microsoft Word, Excel, and PowerPoint. But wouldn't it be great if you could actually synchronize those kinds of documents between your PC and the suite? You can with DocSyncer, a free tool that's currently in beta. Though intended to make your files accessible anywhere you go, it also creates a perfect backup of your Office documents within Google Docs (and, for that matter, a backup of your Google Docs documents on your PC). Currently the beta is limited to syncing files contained in your My Documents folder, so you may have to do a little shuffling if your files reside elsewhere.