just download mac os x tiger ( Mac.OS.X.Tiger.CD.Kit ) from
http://thepiratebay.org/details.php?id=3344152 ( torrent )
Once you have an install disk cd1 power on and press C until your ibook boots from CD, don't install the OS again! Just click through windows far enough until you get the regular set of choices on the menu bar. One of those menus is Utilities and one of the choices on that menu is Reset Password....
Br.