Unfortunately I can't find it any more, and I can't remember its name but there is a product designed for education establishments that goes one stage further. It allows you to set up windows as you want it and then everytime you reboot the system windows is restored to that format. That is ALL changes made during a windows session are completely lost (including registry changes, files saved etc.).
You could exclude other partitions from the restore so that you can save files separately during work and not have them wiped, and there was a command console which could unlock the system so you could make changes.
The programme also locked modification via BIOS hacks.
Originally designed for schools, so that you could always simply press the reset button and get a standard system, I toyed with the idea of using the system at home too for people sharing my computer. Seemed a bit like overkill to me but you may find it useful.
I will wrack my brains and see if I can find it or remember what it was called ... anyone else know what I am talking about?