Ah, nothing like a good highjacking...

Apart from the use of MS or M$, I use neither. I just type Microsoft.

However, to your issue. I recommend the Microsoft Shared Computer
Toolkit. I believe it's still a little buggy, but it does the trick.
You can configure your user's computer to be nothing but a desktop of
icons that only you want.

There is one feature I recommend you look into. I forget the actual
term for it, but it's a method of locking the harddrive down in a way
that prevents him from making any changes. It works by storing a
complete copy of the OS on a hidden partition of the drive. When your
user logs in, that partition is loaded into the visible one, and any
changes he makes (software, settings, cookies, internet history, etc.)
are all stored normally in the visible partition.

Here's where the cool part comes in. When the user is done, he shuts
down. At this point, the entire visible partition is dumped. Next time
he boots up, the hidden partition is loaded and he's back to a computer
that's virus-free, malware free, etc-free even if he loaded it to the
seams on his last use.

You can set aside an area for the user to save things to that is
retained between reboots. Fear not, however, he shouldn't be able to
install software there since the toolkit can prevent him from running
ANY *.exe file.

If you have any questions, drop me an email.

Enjoy.

- wulf