Oh... I am running Windows 7 Pro. So all I need is the SDK? 7.0, 7.1 or 8?
SDK version has nothing to do with OS you are running.
SDK is providing header files and libraries that your code wants to use it. If you install older SDK version, you won't have access to APIs available in newer Windows versions (unless you declare & load these symbols manually). But that may be OK with you. Then using older SDK version is OK. Just don't expect best compiler there. It will give much older cl.exe/link.exe versions, probably from VS2013 or similar.