Would it not be technically possible to override hotkeys like Ctrl-Alt Esc and perhaps even Ctrl-Alt Del with Hotkey, making basic functions inaccessible and thus the possiblities for computer use very limited (I'm not 100% sure on this). A theme such as this would probably only need a taskbar module, a clock label and IconDesk. Easy to do yourself by crippling an existing simple theme.

However, my dad let me play with DOS and stuff when I was eight, and I never managed to break it. :)