Microsoft have produced a (free) tool called Steady State to make it easier to manage shared computers. It may not be quite what you're looking for, but I noticed it has a 'Disk protection' mode which allows you to set an auto delete setting which removes changes made to the computer every so often. Here's a screenshot tour
Screenshot Tour: Kid-Proof Your PC with SteadyState And here's the product homepage
Windows SteadyState