You Had Me at EHLO just posted some information on Exchange 2007 SP1. This one stood out - it will be a bit before Windows Server 2003 SP2 is implemented. Of course, it will be a bit before Exchange 2007 is implemented! Regarding the operating system, SP1 for Exchange 2007 will require Windows Server 2003 SP2. This will be a hard dependency for installation, so the operating system must be upgraded to Windows Server 2003 SP2 before you upgrade the Exchange 2007 RTM installation to Exchange 2007 SP1, ......