"I have the old-school stuff, the MadCatz-era stuff: two throttle quads, Cessna rudder pedals, Cessna trim wheel and Cessna yoke, they all run on XP..."
"...they say Win7 and up."
If you're using XP now and they work, good.
Are you thinking of buying additional Logitech/Saitek products? If so their "updated" driver software may give you problems.
Fortunately, that's not a problem.
There's a free program called SPAD
. Not only should it work with XP, it will
give you MUCH better control over your Saitek hardware.
If you go with SPAD the first thing to do is to uninstall all of your Saitek driver/software.
If you have a Saitek Pro Instrument Panel, there is a Saitek driver just for that, but I'd have to look for it as I don't use it.