By administrative password, I am guessing you mean the password for the root account. If you can boot the computer from a CD, then you can use a live CD to save yourself.
Boot to the live CD of your choice. If you are unfamiliar with live CDs, KNOPPIX
is a good choice. If you use KNOPPIX, mount points will already be created for you. Mount your root partition read-write. I'll assume it is mounted to /mnt/hda1. If not adjust the following command accordingly. Run the following as root:
chroot /mnt/hda1 passwd root
This will allow you to reset the root password. When you reboot you can login to the root account with it.
As a security matter, you need to realize that if you can do this, then anybody else with physical access to the computer can do it too!