I want the operating system (Windows) on its own hard-drive with nothing else. That way if the operating system hard-drive fails, I only lose the operating system. I can always go get another copy of Windows. After I get a new drive and Windows, I still have all of my old files. Thus, I put my files on hard-drives I replace regularly or back-up, and software on drives I don't care about. It's fine to allow a hard-drive to fail if there are copies of the files on that drive somewhere else.