Microsoft has launched an interactive tool in the Q&A format that will be a sure help for your exchange 2010 deployment. Tool is named “Exchange Deployment Assistant” in shot EDA.
To learn more about EDA you can visit Exchange Deployment Assistant page.
Currently the tool is supporting Exchange 2003 to Exchange 2010 upgrade path only. Hopefully, other transition and upgrade paths will be available soon.
Please do feel free to comment if I have missed on adding something here.