The default user already has administrative access to the machine! This is the exact definition of jailbreak... If I can read and write any files and I can read and write all registry keys, what else do you want? You have full, root, control of the machine... There is no jail!
> Microsoft thinks about security very seriously, unlike certain Linux developers and vendors.
Now I will have to think you are just trolling me. Are you? Sorry I have fallen for it.