Hi all!
I don't have the administrator password how can I enter the windows XP
as administrator?

thanks!

Is it your personal system? If so, then why don't you have the password?

no,it isn't mine.
I am permited to use some systems in my university but just as a guest!
so i have some problems with guest and i'm looking for some way to be an administrator

Then I'd suggest talking to your school's administrator or whoever owns the computers about getting you the privileges you need. Chances are you'll be violating any "computer use policy" you signed (if you did).