To reset your OS X password without an OS X CD, you need to enter terminal and create a new admin account:
1) Reboot
2) Hold Apple + S after you hear the chime
3) When you get text prompt, enter in these terminal commands:
3a) mount -uw /
3b) rm /var/db/.AppleSetupDone
3c) shutdown -h now
4) After rebooting you should have a brand new admin account.
When you login as the new admin, you can simply delete the old one and you're good to go again.
