Execut .reg file before boot

basically what I am trying to do is hide my one and only admin account on Vista.
Got that but I need now a way to bring that account back from hiding whenever I need it and it needs to be as automated as possible.
I can do it with Spotmau and use its Registry editor but that involves too much fondling around for the people using it.
Basically the idea is to pop in a flash drive, turn the computer on and something loads up, makes the registry change needed and done...

How would i get around to do that?