With all of the new classes in 2.0, I sometimes find myself guessing at the dll's in order to find out how to reference them in a project. Case in point: with the MONAD namespaces (System.Management) , I didn't realize that they were actually found in the “Program Files\Longhorn Command Shell Preview” folder. Another point (from 1.1), the System.ComponentModel.Design namespace is actually held in System.Design.dll. I was recommended to use Reflector to search for the classes, but what about classes that are not included in the framework?