Synchronising databases / database technologies

I need some advice before we engage in some costly development work We have two SQL Server database servers on the same network. One runs an in house database and the other a proprietary database that we bought in. We want a couple of tables between the two to be synchronised (customer details / contact details) Now if I were doing this I would create a trigger on a table in database A that when updated calls a stored procedure that updates a table in database B. And vice versa to keep the records in synch with an appropriate flag that activates the trigger. The creators of the proprietary database that we need to interface with have proposed creating a network service that picks up changes in our database and extracts the data back to their own. And the transfer can only be one way by their service because of 'record locking'. Without making any assumptions is this really the best way to do things? Thanks NB both databases are running on SQL SERVER 2005