CC mail and Exchange 4. You should also know what is considered a licensing connection. Does web clients need to have a separate client access licenses each or do they use only one license for all web clients. If you have the Transcender of Exchange4, do not concentrate much on this for the Exchange 5 exam. Questions are entirely different and only 3-4 questions have similar scenarios.
Online manual is the best study guide.
Playing with the Exchange administrator will also help.