- The servers need to be running on Windows Server 2008 or Windows Server 2008 R2;
- .Net framework 3.5 with SP1 needs to be installed;
- PowerShell 2.0 needs to be installed;
- Office Filter packs needs to be installed for the Hub Transport Server role and the Mailbox Server role;
Make sure that after installing Windows on the servers that they are up-to-date with the latest hotfixes and service packs.