ExMon is free tool that  allows an Exchange administrator the ability to see in detailed performance of an Exchange server.  Shown on a user by user basis, ExMon allows you to see how much CPU, latency, network traffic, and disk each user on an Exchange server consumes.  It captures data sent back to the Exchange server from Outlook 2003 and higher about the user's actual experience, showing the actual RPC (network+server) latency and even the name of the process talking to the Exchange server (so you can see ActiveSync usage and other 3rd party MAPI applications).  http://download.microsoft.com/download/3/5/b/35b64e21-44b6-4d30-b4d2-3a41f3635e7e/Exmon.msi