hoffmandirt

I am designing a database where there will be website users(registered users) and non website users who will just call in and a support admin will enter in the request. I am not sure how to set up the tables in the database. Should I have one users table that stores contact info and login info and leave login info blank if the user is not registered, or should I have two tables, one that stores all user contact info and one that stores only user names and passwords for registered users and links to the contact info table. This shouldn't be this hard i don't think. I must be looking to deep into it.