On XP, you're Hawkmoon. You are
also the "default user", I believe.
The "Administer" is kind of a hidden account that can only be gotten to in a couple of ways. I think Microsoft set it up that way so that they had an easy way of allowing people who forgot their passwords to get back into their accounts, as all Administers can change passwords of other accounts on the computer without needing to know the existing password.
Unfortunately, it also allows a backdoor onto a password protected computer for people who know about it, as people rarely password protect the administer account.
As a side note, if you are not computer-savvy enough to know this, and you are sharing an apartment or dorm room with someone who is, many shenanigans can occur, as
my...I mean some roommates have found to their dismay.