Exchange 2010 Prerequisites

When installing any Exchange 2010 role ensure you check out the Prerequisites. This site tells you exactly which roles and features you need for each exchange server. It even shows you how to use the handy scripts that come with Exchange 2010 so that Exchange 2010 installs the Roles and Features for you. This is a must read article if your setting up Exchange 2010 in your organization:

http://technet.microsoft.com/en-us/library/bb691354.aspx