[Update: See Visual Studio 2010 Native Multi-Targeting]
Many of you use my VC Build Hook utility to target multiple versions of AutoCAD from a single solution in Visual Studio 2008. Visual Studio 2010 now includes a new feature called native multi-targeting that performs the same function as VC Build Hook. The new feature works great for using build tools back to VC 7.1, but it does not work with VC 7, which is required for targeting AutoCAD versions 2006 and earlier.
The problem is that VC 7 chokes on Unicode response files. In earlier versions of Visual Studio you could set a project property to select Unicode or ANSI response files, but that property has been removed in Visual Studio 2010. I have been told by a Microsoft engineer that the problem will be addressed in SP1, presumably by adding that project property back.
The moral of the story is that you’ll need to wait for SP1 before you’ll be able to use the VC 7 build tools from within the Visual Studio 2010 IDE. I am not planning to update VC Build Hook to support Visual Studio 2010.