Which Windows should I use? I just got an Arduino Mega 2560?
Whichever you prefer and that is compatible with the rest of your computer. Version 1.8.2 of the IDE is compatible with all versions of Windows from XP onward.
Versions 1.8.1, 1.8.0, and the 1.6.x and 1.5.x versions are incompatible with Windows XP, but that bug was fixed in 1.8.2
I prefer Win7. May be hard to get other than Win10 these days. Support for older versions has been expiring.
Has anyone used 2560 with a windows 10 successfully ? I have a Mega which had been working fine on an XP until I bought a Win 10 laptop on which the COM ports do not load. Any leads ?
Did you check hidden devices on win 10 ? Dont ask why they hide the com ports I have no idea but on win 10 they are under hidden devices.