With the release of Exchange Server 2010 Beta 1 (download), many of you have been asking where you can access a 32-bit version of the product. Microsoft has confirmed of “not shipping a 32-bit evaluation version of Exchange Server 2010”.  So where does that leave you for the following scenarios?

Lab Environments - you can leverage Hyper-V (download) or other virtualization platforms found on the Windows Server Virtualization Validation Program to provide support for 64-bit guest operating systems. For rapid evaluation, MS will provide pre-configured VHD images for use with Hyper-V.
Demo machines - Exchange Server 2010 will require a 64-bit server operating system. In addition, you can employ virtualization technology that supports 64-bit guest operating systems to support demo environments.

More info: Exchange Blog