Password Protection

On my XP HE I have password protected Admin Acoount and Guest account which anyone can log in and use the PC.
My 16 year old relative has been staying with us for the last couple of days and I have noticed that he got rid of my Admin account and went into Internet, downloaded few programs :mad:.
I was very annoyed.....What is the point of having an Admin Account if it is that easy to change the whole set up?
Is there anything else I can do to protect my Admin Account please?

Sounds like he used or at least guessed your password to alter the system have you tried setting it up with a more complicated password which includes numbers and letters?

Or you may have left the default, normally hidden, Admin account unprotected. Anyone can access that if it too doesn't have a password. Go to Start>Run and type "control userpasswords2" without the quotes, and you can set the password for it there.