correction: Exchange Server 2010 System Requirements

R2 is not the minimum requirement.

http://www.microsoft.com/exchange/2010/en/my/system-requirements.aspx

To run Microsoft Exchange Server 2010 Enterprise Edition on x64 platforms, you need:


PC―An x64 architecture-based computer with Intel processor that supports Intel Extended Memory 64 Technology (Intel EM64T) or AMD processor that supports the AMD64 platform; Intel Itanium family IA64 processors are not supported.



Operating system―Microsoft Windows Server 2008 x64 Standard and Enterprise Edition with Service Pack 2 or Microsoft Windows Server 2008 R2 Standard and Enterprise Edition.



Operating system for installing management tools―The 64-bit editions Microsoft Windows Vista or Microsoft Windows 7 or Windows Server 2008. Note: Requirements only for management tools installation.







Additional requirements to run Exchange Server 2010

Memory―Minimum of 4 gigabytes (GB) of RAM per server plus 5 megabytes (MB) of RAM recommended for each mailbox.



Disk space

At least 1.2 GB on the drive used for installation.



An additional 500 MB of available disk space for each Unified Messaging (UM) language pack that you plan to install.



200 MB of available disk space on the system drive.



Drive―DVD-ROM drive, local or network-accessible.



File format―Disk partitions formatted as NTFS file systems.



Monitor―Screen resolution 800x600 pixels or higher.







Exchange Server 2010 prerequisites

If these prerequisites are not already installed, the Exchange Server 2010 setup process will prompt and provide links to the installation locations; Internet access is required if the prerequisites are not already installed or available on a local network.



Microsoft .NET Framework 3.5 SP1



Windows PowerShell v2.0







Detailed technical requirements

Actual requirements will vary based on system configuration and specific features installed. For more detailed system requirements, please visit the Exchange Server 2010 Technical Documentation Library.







Additional requirements

Windows Server 2008 R2 requirements