you can't, win xp comes from win nt, there's no password for the screen saver, you can choose if when the screensaver activates the workstation is locked or not
hope tha helps
i dont get the password option in xp home. u do however get the tick box option "display welcome screen on resume" so it returns 2 the welcome screen when u stop the screensaver. which basically does the same but means outher users can logon rather than have 2 get ur screensaver password so they can do some work