The Windows DDK contains a variety of build environments for different operating systems and processors. These environments are all named for the binaries that they build, not the operating system that the build occurs on. For example, choose one of the Windows XP build environments to create drivers for Windows XP systems.
With one exception, you can use any build environment on any computer. For example, you can use the Windows 2000 build environments on a Windows Server 2003 computer to build binaries that will run on Windows 2000. Or you can use the Windows Server 2003 64-bit build environment on a Windows 2000 Professional computer with an x86 processor to build binaries that will run on an Intel Itanium computer with Windows Server 2003.
The one exception is that you cannot build 16-bit binaries (such as virtual device drivers or boot loaders) on a 64-bit computer (such as Itanium or AMD x86-64). When you install the Windows DDK on a 64-bit computer, the 16-bit build environments will not be available during installation.