Not to ask too stupid a question, but why would you want to have a "machine" account? Would not the user account suffice?
The Samba packages contain a book called: "The Oficial Samba-3 HOWTO and Reference Guide"
Look at Chapter 4: Domain Control -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba
