The Exchange setup requires a Windows 64 Bit Edition to initiate; therefore using Windows 32 Bit Edition isn't supported with installation on the Management Tools from the Exchange 2007 Installation disk. The 32-bit version is for testing only. Many people like to test server software in a virtual environment before making the production plunge, take note that Virtual Server 2005 R2 does not support 64-bit guest’s virtual machines. Even VMware ESX 3.0 only had experimental support for 64-bit guest operating systems. ESX 3.0.1 now includes full support for 64-bit guests, but this is a recent release. Sure, desktop virtualization packages have supported 64-bit guest OSs for a while now, but the enterprise-variety virtualization offerings are just catching up to this. A transition is the process in which you perform an upgrade to Exchange 2007 that is you move data from any legacy Exchange servers in your Exchange organization to new Exchange 2007 Servers, after which you decommission the legacy Exchange servers. A transition should not be confused with a migration, because unlike a transition a migration is the process in which you move data from a non-Exchange messaging system (such as GroupWise, Lotus Notes or Send Mail) to an Exchange organization, or move data from a legacy Exchange organization in an existing Active Directory Forest to an Exchange organization in a new Active Directory Forest. It’s important to note that unlike previous versions of Exchange, in-place upgrades from Exchange 2003 to Exchange Server 2007 aren’t supported, because, among other reasons, Exchange 2007 is 64-bit and therefore requires the x64-bit version of Windows Server 2003; We shouldn’t forget that Exchange Server 2007 also exists in a 32-bit version but this version is meant to be used for testing and evaluation…