If you want to evaluate Microsoft Exchange Server 2010 then you can try this?

You can download this fully configured virtual machine of the latest release of Exchange Server 2010 SP1. Evaluate the new capabilities of Exchange Server 2010 SP1, which helps you achieve new levels of reliability and performance by delivering features that help to simplify your administration, protect your communications, and delight your users by meeting their demands for greater business mobility.

You can download the VHD @ http://www.microsoft.com/downloads/en/details.aspx?FamilyID=53f7382a-3664-4de3-8303-31e514d69f02

Note:
1. This trial software is intended for evaluation purposes only.
2. There is no product support for this trial. You are welcome to share your trial experience with others and to ask for advice by participating in the forums

3. This download comes as a pre-configured VHD.
4. This download enables you evaluate Microsoft Exchange Server 2010 SP1 for 180 days
5. Windows Server 2008 Hyper-V or Windows Server 2008 R2 is required to use this virtual machine. For more info visit the following link.
6. In order to use this evaluation package you will need to have Microsoft Hyper-V installed on a physical machine.