I am sure it is offically supported or not, but I am using it on Windows 7 SP1 without any problems.
As per kB#:KB56386, it's not supported.
Thanks to everyone for your responses. As an FYI for everyone, the response that I received from McAfee Support is that Windows 7 SP1 is supported for the HDLP Agent.
As per KB68147, Windows 7 32 - bit and 64 - bit are supported AND as per KB50473, SP1 is supported within 30 business days of the official Microsoft GA date, unless otherwise specified - which is not the case.
Also FYI, KB56386 mentioned in a response above is regarding environmental requirements for agent deployment from the EPO server - it is not related to HDLP.
Therefore, Windows 7 SP1 is officially supported for use with the latest HDLP Agent.