Hi Chris,
Here's what I think you need to do:
1. Add the reference.
2. In Solution Explorer, open the references node for the project whose references you're interested in.
3. Right-click a reference whose DLL you don't want copied to the debug folder.
4. On the context menu, choose Properties.
5. In the Properties window, set the Copy Local property to false if no copy wanted, true if copy is wanted.
That should give you the control you want.
Cheers,
ChuckforDummies
Co-Author of C# 2005-2010 for Dummies