Read-Only Desktop

Hey ppl,

I work for a small internet cafe and Users keep coming in and saving files on the desktop, which i don't mind about that much, except that mostly it is explicit material and when kids come in to use those computers later they have access to it. All other drives and stuff are disabled. I want to make the desktop Read-only and I was wondering if anyone knows how to do it? maybe in the regisrty somewhere? Also, because of the same problem i was wondering if its possible to delete "My Documents" or at least hide it?

Cheers for any help.

Andy