As you will be writing code, you will probably be writing tests. And you will probably come to writing internal methods to limit their visibility. And it will be necessary in lots of cases to test also these internal methods. How to do that ? You won't be able to access them from your test project.
It's not a big problem as Visual Studio 2005 (and 2008) will generate accessors for you using reflection. VS 2005 will generate a code file (that will have the big disadvantage that when you will change the name of a method, the file won't gets generated and your project will continue to compile. VS 2008 will generate an accessor DLL that will gets compiled (and so re-generated) at the same time you build your project.
But there is also another way to test the internal members : using the InternalsVisibleToAttribute.
I will show here in this post how you can do that for an unsigned DLL but also for an assembly signed with a strong name. [Plus]