I set up a Samba PDC, added some machine accounts and user accounts, and later decided that I needed to change the domain name (it was the same as one of my user accounts, which caused all manner of trouble under XP). Doing this did not produce the desired result, as the passdb.tdb file still contained the old domain name in the user/machine records, causing continued (but less severe) confusion for XP. It seems to me that a Samba PDC ought to detect when a user/machine account record contains a domain name different than the domain administered by the PDC, and fix the record.