If you’re running 32–bit OS (Host OS) on the physical host platform, and want to test Windows Server2008 R2 without installing it on a physical 64-bit platform, because there's no such thing as 32-bit in the Server Core. Here comes Sun VirtualBox that endowed host environment with a way to host 64-bit guests in a 32-bit system. Just download: VirtualBox | Windows Server 2008 R2 Beta (Windows 7 Server), and read our Windows 7 Beta 1 installation guide with Virtual PC 2007 SP1.