Exchange in a Sandbox
Two guys I work closely with in the UK, Greg Taylor and Simon Shepherd, have written a great article on provisioning and simulating Exchange in a Sandbox. It explains everything you need to know about:
Calculating IOPS
Configuring JetStress
Gathering data with Exchange Profile Analyzer
Exchange Server 2003 Load Simulator
Exchange Server Stress and Performance tool
A great reference document and certainly worth a read to make sure your Exchange estate is available and reliable..!
EDIT: Sorry forgot to actually add the link..! :) You can access it here