Hi,
Based on my research, Message Queuing Downlevel Client Support Service is being removed from Windows 7 and Windows Server 2008 R2.
You can install Message Queuing server on Windows 2003/2008 machines.
Microsoft Message Queuing
http://technet.microsoft.com/en-us/library/ee681715(v=ws.10).aspx
Microsoft Message Queuing (MSMQ) - Removal of Windows 2000 Client Support Service
http://msdn.microsoft.com/en-us/library/windows/desktop/dd371738(v=vs.85).aspx
Hope this helps.
Jeremy Wu
TechNet Community Support
