I stumbled across this link today that I never knew existed. I have always had a hard time locating trial software, but look no more. Here you will find links to download the following products, enjoy!
Server Products and Technologies
•BizTalk Server 2006
•Commerce Server 2007
•Windows Compute Cluster Server 2003
•Microsoft Office Communications Server 2007 and Microsoft Office Communicator 2007
•Exchange Server 2007
•Identity Integration Server 2003
•Identity Lifecycle Manager 2007
•SharePoint Server 2007
•Windows Small Business Server 2003 R2
•Speech Server 2004
•SQL Server 2005
•Virtual Server 2005 R2 SP1
Server Operating Systems
•Windows Server 2003 R2
Security Products and Technologies
•Microsoft Antigen
•Forefront Client Security
•Forefront Security for Exchange Server
•Forefront Security for SharePoint
•Internet Security and Acceleration (ISA) Server 2006 [Standard Edition]
•Internet Security and Acceleration (ISA) Server 2006 [Enterprise Edition]
System Center Products
•System Center Configuration Manager 2007
•System Center Data Protection Manager 2006
•System Center Essentials 2007
•Microsoft Operations Manager 2005
•System Center Operations Manager 2007
•Systems Management Server 2003 R2
Office System Products
•Live Communications Server 2005
•Office Enterprise 2007
•Office Project Server 2007
•Office Project Professional 2007