Once upon a time, Freddy has delivered a great series on connecting to NAV Web Services from a smorgasbord of technology flavors. If you are a .NET enthusiast, like me, the obvious choice is to connect through the tools that are at your disposal in Visual Studio: the proxy classes.
A proxy class is a class which wraps a Web service functionality into a strongly-typed .NET object, and allows simpler communication through Web services. It hides away all intricacies of SOAP communication, authentication, serialization and deserialization, and exposes simple, easy-to-use objects. Every NAV Web service results in a series of proxy classes, and in Visual Studio the generation of those classes is as simple as clicking a mouse a couple of times.