So, to the hint: from what I've seen, if you create an account named Administrator with a short name of Admin, the computer will automatically hide the account for you. However, this only works when the new Administrator account is the only administrator account in the system.
[robg adds: I tested this hint, and (somewhat to my surprise), it does work. Case matters, though -- make sure you capitalize the short name! In order to have the account auto-hidden, it does need (or so it seems at first) to be the only admin account. My first test failed, and that's because it was the second admin account on the machine. I then converted my standard admin account into a regular account, then created the new Administrator account. On my next login, the Administrator account wasn't listed in the login screen.
However, after logging in as the new admin, I then switched my standard account back to administrator and logged out. This time, the Administrator account stayed hidden. So it seems it has to be the only admin account when it's created, but after that, it will remain hidden if you add additional administrators.]

