Similar to this there is a program I use called Faronics DeepFreeze. It allows you to freeze a drive (the OS drive is what I use it for).

The difference is that it allows writes but any modifications are removed on reboot. I use it to lock down public access machines, users get a network drive they can write to but without being able to modify the OS they can't do much damage.

Not the solution your presenting but it works pretty well.