Install Microsoft Office Communicator on Windows server 2008

Hi,

I have Windows Server 2008 Enterprise 32- Bit Beta 3 kit installed.
I need to install Microsoft Office Communicator server on it. I tried
installing Microsoft Office Communications Server 2007 Trial but it
gives the following error:

Not available: Standard Edition Server can be installed only on the
following operating systems: Windows Server 2003 with SP1 and any
later service packs, Windows Server 2003 R2.

Can anyone please suggest how can I install Microsoft Office
Communications Server 2007 Trial on Windows 2008 server. If this is
not possible can anyone direct me to the correct installation file.

Regards,
Swapna.