Not the sort of thing I advocate using, parental controls on computers, but it exists and it is part of the Windows Live Package(its optional though), so I think I ought to review it.
You can then control it from the web interface.
Fortunately, a password can disable it, and you can uninstall it quickly….done!
So, if you use this, make sure the person you want to block stuff from doesn’t know the admin password.