Was just thinking, as the PMDG recommendation is to not follow the "FSX tweaks" regarding shutting down various Windows services what is the esiest way to restore them? Any sort of "restore windows to default" button, or is it a matter of following those guides "in reverse"?

I think you have to do the guides in reverse... In the days when I still did these kind of things (I think it's rather useless now), I ALWAYS noted exactly what service I changed, because you never follow those guides to the letter. I guess you didn't do that, so... good luck with it! (Maybe doing a fresh OS install is done quicker, I don't know. ;) )

Suspected as much. The "hard" part will be to find the actual guide, after that most, but not all, should be a matter of doing the "reverse order" :D *fingers crossed*

as far as my windows knowledge goes you can check which services are disabled by running the command 'msconfig' --> go to the 'Services' tab --> all disabled services will be unchecked --> 'Enable all' and you should have the 'default' Windows setup.

Also go to run/services.msc and find all entries with disabled for startup type.

The tips about 'disabled' are nice, but be default there could already be some services disabled... And some services might have gone from automatic to manual or the other way around. Those guides are not only about 'turn on' or 'turn off': there are more options and simply enabling everything that is disabled might lead to unwanted results...! I am installing my new pc right now and I will leave all the services alone, that's for sure. I only do some OS tweaking using the regular Windows options (indexing off, not all those fancy aero features, etc.) and that's it. Saves a lot of time and a lot of potential problems. ;) And I really think that with a modern computer it won't make much difference at all for performance.