Have now got both the laptop and main PC upgraded to run Windows 10. Unfortunately an almost tragic downside is that both FS9 and FSX have serious issues trying to run on the new operating system.
After a bit of Googling and some adjustment to the cfg file, have managed to get FS9 running in windowed mode. Trying to run full screen simply ends up with the monitor going black with mouse cursor spinning, can't Alt-Tab or run Task Manager, had to kill it with a hard re-boot.
FSX (patched boxed version) I have managed to get the front end UI (menu screen) to load but as soon as I click a button to select an aircraft or arrange a flight it just freezes up.
Loads of references to issues on MS' own Help site, but few answers forthcoming from them as both seem to be regarded as old and unsupported software. That might be the case, but unless you are prepared to go down the questionable legality of using Prepar3D for "entertainment" or X-Plane (if that works) they are still the most current comprehensive civilian flight sims available. Most users over the years have probably invested several £100 in hardware and software add-ons.
Just wondered what experience others have had getting FSX in particular to run. Would it help to buy the DTG/Steam version as, presumably, Dovetail are at least trying to update it for Win 10 otherwise they're not going to sell many copies as more and more people move to the new O/S.