Compaq Armada E500 Pentium III 900Mhz laptop

Question

10 Year old daughter got this for christmas. She put password for administrator and one for her. Well she kept on changing passwords from her 21 year old sister in car going home in dark and bumped her and can't get in now because it is wrong password. I can get into safe-mode but how can i get to chane passwords well she played with notepad for a little It was just bought on e-bay and Windows XP Pro installed!!!, WiFi wireless card Can someone help me if need to reply [e-mail]
thank you for all responses given No CD came with it She is driving me crazy.