The Visual Studio C++ compiler provides the command line compiler options /favor:AMD64 and /favor:INTEL64 to optimize for AMD64 or Intel64 processors respectively. Now, the terms AMD64 and Intel64 are essentially interchangeable for most purposes, but there are some differences that the compiler can optimise for.

On Microsoft Windows 7, is there a reliable way to check at application install time whether we're installing on an AMD64 or INTEL64 system?

I'm using InnoSetup and WiX for installers, and I'm speculating about selecting the version to install based on AMD64 or INTEL64 CPU.

Edit: Some notes in retrospect

In the end, the answers from RRUZ and Andrew Cooper both gave good solid strategies for approaching this issue, but as neither of them are really firmly future proof, personally I'm going to stick with the default /favor:blend for my project.