You did not state which version of windows you are installing. If it is a bios password, remove the battery or use the jumper. Which ever is easiest and available. Be sure to unplug the computer first.
If it is a windows password, you can use a bootdisk to boot and then format the drive. you will need to go into the bios when starting and make sure it is set to boot from floppy first.
If you need a boot disk, go to the link below and donload the one you need. After you download it, put a floppy in and open the file and it will make a bootdisk for you.
http://bootdisk.com/bootdisk.htm