Loading appropriate interop of Office/Visio

Hi,
I am creating a .Net application to interact with Visio.
For now I am making it working with Visio 2003 only as I added the visio 11.0 tlb reference from the project->references.

The code that uses the interop class and interacts with visio is already written. what should I do to make it work with other versions of office atleast the newer ones.
so that the application loads the interop from the relevent version of Visio..

Any sample code would be helpfull.

Thanks,
Ahmed