We are on Windows 2003 servers with Exchange 2003. Would it be best to migrate to Windows 2012 with Exchange 2010 or go to Exchange 2013. The Macs have Mountain Lion/Mavericks installed and currently use Entourage 2008. Could we continue using Entourage 2008 with Exchange 2013 or should we move to Outlook 2011 and Exchange 2013? Are there any issues in using Outlook 2011 and Exchange 2013?