Windows 2008 R2 will be 64-bit only
From the horse’s mouth at at the Windows Server Division WebLog:
“First and foremost, 32-bit is done. History. Archives. Windows Server 2008 R2 is the first Windows OS platform to go 64-bit only, and frankly it was high time. Customers have been unable to purchase a 32-bit server CPU for over two years now, and the advancements in CPU architectures really dictated that we squeeze as much performance out of customers’ hardware purchases as possible. The move to 64-bit is a first step.”
SQL Server database administrators everywhere are probably clapping with delight, but that clapping may slow down a little if you use virtual machines on your desktop computer for testing or development. If you’d like to run Windows 2008 R2 as a virtual server guest, that means you need to be running a 64-bit host – which means your laptop or desktop will need to be running a 64-bit version of Windows.
Update: fellow Questie David Gugick points out that you can still run 64-bit guests on 32-bit host OS’s as long as your underlying hardware is 64-bit compliant.