If the Windows SDK for Windows 7 SDK (RC release) and Visual Studio 2008 RTM are installed on a machine running an x64 version of Windows, the following issue may occur. The Itanium and x64 listings are missing from the New Platform drop-down lists of the New Project Platform and New Solution Platform dialogs of the Visual Studio IDE. (This issue will be fixed in the RTM release of the Windows SDK for Windows 7.)
This issue will occur regardless of the order of installation – Windows 7 SDK (RC) and then Visual Studio 2008 RTM, or Visual Studio 2008 RTM and then the Windows 7 SDK (RC) unless Visual Studio 2008 SP1 is installed before the installation of the SDK.
The issue occurs because 64 bit versions of VCProjectAMD64Platform.dll and VCProjectIA64Platform.dll are installed instead of 32 bit versions. To prevent the issue install Visual Studio 2008 SP1 before installing the SDK.
To determine if your VC++ directories are missing, launch the VS IDE and go to tool->options->projects and solutions->VC++ Directories. If the entries in the drop down “Platform” box appear as "x86", "x64" and "Itanium", your directories are as expected and you do not have this issue. If the platform entries appear as "x86", with no entry for "x64" and "Itanium", you do have this issue and can use the workaround.
Workaround: If your Visual Studio installation has already been affected follow these steps to address this issue:
Note: Running “Repair” on the Windows SDK will revert these fixes.
The MSDN Windows SDK Developer Center is the place to find resources and links to Windows SDK products, release notes, technical articles, and more.