If you know how to burn an iso cd, you can burn/create an "Ultimate Book Disk", which contains tons of useful utilities. One of the utilities is in the "NTFS Tools" Section, and it's called the "Offline NT Password and Registry Editor". What it does is take you through a few prompts, and asks you if you want to reset the administrator password. If you choose the default suggestion, the password will be blank after it has been reset. Then, you can exit the program and reboot into Safe mode on the pc, access the Administrator account without entering anything for the password. Follow the instructions given you earlier about setting up another account.
After you're all done with everything, I would definitely go back and give the Administrator account a password.
Here's the link to the Ultimate Boot Disk info, where you can download the iso to burn it: