Exchange Server 2007 SP3 is available for download. This service pack enables Exchange 2007 to be installed on Windows Server 2008 R2 version of the operating system. Also, with this SP3, Exchange 2007 management tools can be installed on Windows 7 machines.
Download Exchange 2007 SP3
Exchange 2007 SP3 requires Schema changes even if you have the RTM version of Exchange 2010. You can see these details on the following link: