I actually like how the boxes at my school are setup. Everything is locked down--no browsing of the C: drive and no saving or modifying of any files. If we want to save something it's either to a flash drive or floppy. A modified start-bar along with disabling right-click on the desktop and disabling the command prompt also go a long way.
This keeps the boxes clean and void of any malware since nothing can be installed.
Of course I always keep a copy of Portable Firefox and even a copy of Damn Small Linux on my flash drive for those certain occasions.