Panasonic TZ Password Protection Problem

Hi

I my flatmate has moved out and has left his laptop .

I tried switching it on yesterday but it is prompting me for a password before windows starts .

I tried to format it but cant seem to find out how to do that .
Is there any way that i can bypas the password .

It has vista on and i am looking to install windows xp onto it .
I have got the CD but i need to get rid of this dam password .

Any help will be much appreciated
Thanks