If you're looking for a convenient, uncomplicated, and stable synchronization tool, you could do much, much worse than Microsoft's SyncToy. Part of the Windows XP PowerToys add-ons, this tool makes it easy to keep folder contents identical on one machine or across a network.
The first time you run it, SyncToy will guide you through creating a pair of linked folders. Labeled as Left and Right, it will then ask you to choose from one of five synchronization methods. Echo works like a standard one-way sync, copying all files from Left to Right. Synchronize is bidirectional; Contribute works like Echo but it won't delete files removed from the Left folder; Subscribe only updates files in common that have been updated; and Combine merges Synchronize and Contribute so that files are updated in both directions, but none are deleted. SyncToy does support encrypted files.
SyncToy also offers up a preview, preventing accidental loss of data. However, the two feature omissions are hard to ignore: you can't synchronize across the Internet, and there's no scheduler. For the former, Microsoft does offer a different tool, FolderShare, but by requiring users to manually sync all folders leaves SyncToy behind other free backup apps.
The easy to use, customizable application helps you copy, move, rename, and delete files between folders and computers. There are files from all kinds of sources that we want to store and manage. Files are created by our digital cameras, e-mail, cell phones, portable media players, camcorders, PDAs, and laptops. Increasingly, computer users are using different folders, drives, and even different computers (such as a laptop and a desktop) to store, manage, retrieve and view files. Yet managing hundreds or thousands of files is still largely a manual operation. In some cases it is necessary to regularly get copies of files from another location to add to primary location; in other cases there is a need to keep two storage locations exactly in sync.