That's what I do, with True Acronis. But even that is too complicated for a girl unless you sit there and explain how to do it. The problem is, You (the OP) become tech support for her. Any problem and she's going to push a button trying to go back in time, screw something up, and then call you. The built in Window7 stuff is crap, only backs up files, not the registry. I've heard Windows8 is better. You'll have to suggest an external USB drive for the images.In the real world we call "backing up Windows" making a good workstation image.
TimeMachine is an external hard drive