Just a quick heads-up on support for Exchange 2007. Mainstream support for Exchange 2007 ended on April 10, 2012 and Extended Support will end on April 11, 2017. Rollup updates might be made available for another 2 years but you at this moment you should be planning to upgrade your platform.
More problematic is the underlying Operating System for Exchange server 2007. I have several customers running Exchange server 2007 on Windows Server 2003 R2 and Extended Support will end on July 14, 2015 as shown in the following figure:
If you are running Exchange 2007 on Windows Server 2003 R2 you want to avoid any any “Windows XP” situation with your platform so the call to action is to start planning your platform upgrade now!
More information can be found on the Support Lifecycle pages: