Use old Windows machine as a backup for OS X?

So recently people have been talking about backing up their computers in case something goes wrong and I remembered that I actually do not have a backup on my main machine. So I have an old Windows machine with 500 gb hard drive running Windows 7 and was wondering if I could use that as a backup machine for my Mac running 10.8? I've only used 100gb of my Mac so storage shouldn't be a problem. Thanks in advance for any solutions offered.