This is Microsoft's DirectX 9.0 Software Development Kit (SDK) Update for AMD-64 (Developer Preview) release. This Preview Release is specifically to support those working toward AMD64-bit applications. We are making it available to all beta participants, but this release likely only applies to a small number of developers. In essence this release is much like the DirectX 9.0 SDK Update (Summer 2003), however we have added support to for 64-bit application development. It will install on to both 32-bit and 64-bit environments, but with some differences. In addition to the rest of the SDK components, on 32-bit systems the 64-bit libraries and 64-bit sample makefiles will be installed, allowing for compilation of 64-bit applications. On a 64-bit systems, the 64-bit libraries, 64-bit sample makefiles as well as 64-bit sample binaries and 64-bit utilities will be installed. You will however see that not all samples and utilities are supported on a 64-bit systems. Some utilities will be missing from the 64-bit utility folder and unsupported samples will not have 64-bit binaries or makefiles. This is by design as not all utilities are required to have 64-bit counterparts and some samples either show functionality unsupported on 64-bit systems or we had difficulty getting the sample to work properly in this Developer Preview.