Contacts in Active Directory

Our organization is evaluating Active Directory as a metabase for user authorization from multiple systems.  We have many employees that do not have computer access and thus we do not wish to create User accounts for them.  We are considering creating these users as contacts so that we may look up their employee ID, departmental and management info.  What we are wondering is how difficult is it to "promote" an employee from a contact to a user?  How hard is it to "demote" a user back to a contact?  We are aware that there are scripted solutions that involve reading an existing contact, creating a new user, copying information from one entry to another and then deleting the original, but are there other methods?