I think you should build Python.exe with the option to be statically linked to the VC++-runtime. This way, the executable is a little bigger, but you ensure nobody will have troubles with some VC-runtime different Dll versions.

DETAILS : (I posted it also there http://stackoverflow.com/questions/32748932/python-3-4-3-works-on-windows-vista-but-not-3-5-0-because-of-vc-redist-package )

I am on Windows Vista 32bits. I downloaded Python 3.5.0 but I got the famous api-ms-win-crt-runtime-l1-1-0.dll problem. Then I installed many Visual C++ Redistributable Packages (I tried the 2015's one, then 2013, and 2012) but none of these packages installed any .dll of the correct name. Then, I tried to download a previous version of Python, the 3.3.2 win32 release, I got the same problem !

----> Then, I downloaded the Python 3.4.3 Win32 release, and this-one worked immediately. I suspect that version to have been statically linked with the VC-runtime. This clearly lacks of coherence, some Python releases work, while others don't. So I hope some of the Python developers will see that message and will be able to build some binaries compatible with Windows Vista and the VC-redist-packages.

Question : did anyone understand where that api-ms-win-crt-runtime-l1-1-0.dll comes from ? I suppose it is related to the VC++ compiler options used when building Python.exe (on my VS2010 I have the options code generation/runtime library/multi-threaded, static or dynamic and general/platform_toolset, V100, V110, V120 or V140) ?