chntpw works pretty well too..can clear the sam file
This tool you mention will NOT work on 2000, 2003, 2008, 2012, or any of the server versions. On a server, once you promote it to a Domain Controller passwords are stored in the Active Directory. They are NOT stored in the SAM, so that tool is useless.
Tools like "NTPW" and the one you mentioned are great for client operating systems like XP, 7, if you are not trying to be stealth.
They are not stealth bc blanking the password will be noticed by anyone. This technique here bypasses the password, but leaves admin password in tact. Person would need to go digging through logs to find you