Disabling Internal Keyboard from startup?

Hi,I’m running XP on a Dell Inspiron 6400.
I spilled a drink on my keyboard and i can’t access my computer because i put a password on.I have tried connecting an external keyboard (usb) which works when i use it to access setup menu but after the win xp screen appears,it is disabled.
Any ideas on how to disable the internal keyboard or at least let it recognize the external?