A. Although changing the account associated with the Exchange 2003 services is possible, Microsoft doesn't recommend doing so. I've had little success making such a change, and my efforts have resulted in numerous errors.
Join John Savill for 9 hours of comprehensive PowerShell training. This course will start from the ground up, walking through the basics of PowerShell, how to create basic scripts, and building toward creating custom modules to achieve amazing results in your environment, in non-Microsoft environments, and in Azure.