Microsoft's Windows Home Server is designed for homes that have multiple computers. Besides file sharing, security and organization of data, it has some great capabilities for backing up and protecting data.
Quoted from http://www.microsoft.com:
Windows Home Server provides automated “no touch” backup for all of the PCs in the home. It will automatically backup your home computers, including the operating system, applications and data, and allow you to easily restore the entire computer or an individual file or folder to a previous point in time. The Windows Home Server Backup solution uses an innovative system to backup only the data that has not already been backed up before. Even if you have several copies of the same data on different computers, the data is backed up only once and Windows Home Server keeps track of what data was stored on each home computer on each day. This makes it very efficient in terms of the time it takes for backups and the amount of space that is used on Windows Home Server.