WoW64 (Windows-on-Windows 64-bit) is a subsystem of the Windows operating system that is capable of running 32-bit applications and is included on all 64-bit versions of Windows -- including Windows 2000 Limited Edition, Windows XP Professional x64 Edition, IA-64 and x64 versions of Windows Server 2003 and 64-bit versions of Windows Vista and Windows Server 2008.

>I presume you mean Windows CE?

No, he means Embedded Windows, like Windows XP Embedded: http://www.microsoft.com/windows/embedded/products/whichproduct/default.mspx.

(What scares me is that you work on embedded systems and have never heard of it. I've never even touched embedded systems work and I know about it.)