...and if you build your own PC, Windows 10 has zero control over what goes on in your bios.
Which brings up an interesting point: Where, if I'm building my own, do I purchase Win10 from? I haven't seen it in any store that sells anything involving technology or computers (and I used to constantly see boxes for Win 7 and 8 all over the place). Once built, it'll boot up to the BIOS, sure, but where's this OS getting into the hard drive from??