There are a few options for this:
- Deep Freeze by Faronics.
- Drive Snapshot
Can he use a large thumbdrive for the image? Leo says yes. Can he just copy the OS without an imaging app? Leo says no, because he won't get the hidden files. Imaging would give him everything.
What about on a Mac? Leo says he uses SuperDuper, which has the benefit of being a bootable backup. He can then have a scheduled backup to an external drive and if the internal drive dies, he can boot directly from the backup drive.