As promised, freeware, open source & liable to lock you out of the house for the night if you aren't careful!
The source code, dlls & compiled exes are in the zip. There's even a ReadMe type file.
Make sure that you have an admin account that this is not running in!
I'd be interested in bugs, suggestions for improvements, posting of improved versions & feedback about which assumptions I've made about Vista (in which this probably doesn't work).
If it all goes pear shaped the registry entries are pretty obvious in the source code.
I've updated this a little, so have moved it to "Share your creations"