access rights

I need a data base to install with my application, but i want that it can
be accessed only by the application. Because it runs on the customer computer
and i dont want he be able to watch into my database. It is posible. I mean:
if my postgres database is on his Windows 2000 and he has the Administrator
password. He have the posibility to view database structure or data? The
only way to access my postgres database is having the postgres administrator
password?

Sorry for english and thanks for your time