Wait. In normal mode of XP home, you can't log in to the administrator account anyway, whether there is a pass or not.
As mrdinkel said, boot into safe mode, and from there you can get into the Administrator account. Of course, if you have set a password for this, your best bet is to use your hard drive as a secondary one, and boot from another.
Sorry. Forgetting your password is tough. I know you must have heard this a thousand times, but be consistant with your passwords. If you must have different passwords for different things alter a letter or something, in accordence with whatever the password is for.