Will:
FYI: Simply using BAT2EXEC will not secure your password (if it had worked in your case). One could easily read your username and password by looking at it in a Hex editor or even notepad. However, since you can redirect the password to SU from a text file, you should be able to pipe the password to it using echo (ie: ECHO password|su administrator "notepad.exe"). Run BAT2EXEC on that, then ENCRYPT it with a program like SECURE.