One other big reason for Linux, is that when your computer starts to bork, you can never be sure if it's a windows or a hardware issue. If you were to call Microsoft, they would insist it's never their fault, but yours or your machine's or your software. Okay, so then you first want to eliminate those possibilities.
So if you booted your machine in Linux, then a lot of your hardware is working. If you couldn't play CDs or DVDs during Windows but can in Linux; if you can burn them in Linux but not Windows, then the problem is likely.. Windows.
If your hard drive tested badly in Windows but not in Linux, well maybe the hard drive is beginning to go bad, but copying your stuff off is harder to do in that situation.. if using Windows.
So even if all you use Linux for, is to buy one of those rescue DVD/sticks (they are Linux programs) or just a Linux stick -- if that's all you use Linux for, well isn't that useful?