WoW64 and 64-bit Hardware
Applies To: Windows Server 2008
Increasingly, Windows server hardware is moving toward a 64-bit platform running 64-bit editions of Windows Server. However, this does not mean that your existing 32-bit applications will not run on Microsoft® Windows® 64-bit versions of Windows Server® 2008. 64-bit editions of Windows Server 2008 provides Windows 32-bit on Windows 64-bit (WoW64), an emulation layer that enables 32-bit Windows-based applications to run seamlessly on 64-bit Windows. This means that, as an IT Pro deploying 64-bit editions of Windows Server 2008 in your enterprise, you can continue to deploy and run your 32-bit applications as you did on your 32-bit systems.
For more information about WoW64 (particularly useful for application developers), see Best Practices for WOW64.