I am looking for recommendations on best non-apple laptops for photo editing. Thank-you!
I used a few times a HP ProBook 13" model. It wasn't the fastest, but it was good enough to use Lightroom CC on 16MP and 10MP files, along with filters and brushes. The screen was surprisingly good for the size (only used it in interiors, though).
I've heard really good things about bigger (15 and 17 inch) models of HP EliteBooks, but look for the workstation models that have the higher resolution screens.
Keep in mind that no laptop screen is as good as a profiled Eizo, not even close, but the highest end models usually have screens good enough if you don't need perfect color accuracy. You can (and should) profile them to get the most out of them, even if you get a MacBook.
What PC will support the last 6 or so operating systems?
If we go back 6 versions of Windows we get: 10, 8 and 8.1, 7, Vista, XP, 2000. While you may be able to install Windows 10 on a PC from 2000, I doubt it would run as well as on hardware from 2010. You can't compare the slow release cycle of Windows OS with the faster paced OSX.