You could, for instance, use Kid-Key-Lock to lock out system key combinations to prevent your little ones (or your own little fingers) accidentally booting out of a game or important app again. Alternately, you can lock the keyboard to just let in letters, numbers, or spaces to help a young typist learn the basics. The mouse can be locked with a similar range of finesse, with individual buttons, the scroll wheel, and double clicking allowed or halted. Kid-Key-Lock is freeware, Windows only.
Of course it may also help your public machines as well - I mean what better way to keep want-to-be script kiddies from trying to mess with your public machines than to shut down the ability to use certain keyboard short cuts. Of course that could also impact the playing of runescape. ;-)