After having hassle from MS over the legality of my Win 7 H64 install (see other thread), I got fed up of the aggravation and cleaned out my hard drive, before installing an old boxed retail copy of Vista Home 64. This other PC is only used for non-sensitive admin and standalone game servers. I also watch TV on it, using media centre, which got ditched for Win 10 (though you can still use it, with some twiddling).
I let it update to SP2, and then downloaded the DCS 1.5.7 installer from the ED website. The installer flat refused to run, so i checked the requirements - Win 7 to 10, basically. I did some research and found no-one seemed able to get DCS World 1.5.7 working on anything prior to 7.
Fortunately, I kept an old installer of DCS World 1.2.4 on a DVD, so I could still go back and fly the many excellent missions and campaigns that are now incompatibel after all the updates changed things vital to their smooth running.
Installed that - on starting the sim, was asked if I wanted to update to 1.2.7 - which I did (new installer update required first). After that, on restarting I was asked if I wanted to install 1.5.7 - which is now installing as I type.
Please note - I won’t be flying anything at all on this - just running it, without graphics, as a standalone server. It can be done.