We currently are running MS Exchange 2007 build 685.25 on Windows Server 2003 R2 x64 SP2 which has treated us well over the years. Hardware is getting tired and we are upgrading and need to install Exchange 2013. We are a bit confused as to what the exact requirements are to run Exchange 2013 along side 2007 and migrate our mailboxes over. Do we need to install specific rollups/service packs on Exchange 2007 before we can do the migration? It seems as though we need to do so but we are unsure of the specifics.