How to bypass default win XP password

Every Windows XP does not have a default password for administrator user. For accessing the system we follow these steps:
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1. log-off your computer 
2. type ++ (delete button is pressed 2 times)
3. After our Logon screen change to classic style then we type username as: administrator and in password fill nothing for login then press enter or login.
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note:-->This method works on fresh installation on windows xp machine. If administrator changes the password it will not work