Question : Downgrade Windows Vista Ultimate to Vista Professional

Does anyone know whether/how to downgrade Windows Vista Ultimate to Vista Professional? I have both licences and 2 laptops, but now need to swap each other OS. Without having to re-install afresh of course.

Answer : Downgrade Windows Vista Ultimate to Vista Professional

Yep the trick worked perfectly fine. As a matter of fact, this trick also works for going from Vista Ultimate to 7 Professional.