you can't see administrator accounts whilst you are using the fast switching user mode...
(where you get all the little icons associated with users at login).
you can log in as administrator, but you'll have to press control-alt-delete...
once you are in you have the choice of either creatnig another user, (which is a good idea, you wouldn't run a linux system as root, and you shouldn't usethe uber admin accuont for everyday windows use either)... or you can switch off fast user switching,