My point was that it made no sense for a non-power user with an older PC to spend $100-$120 to upgrade tor Windows 10, when they could replace it on the cheap and also get Windows 10.
Indeed, for MS believes in marriage, that the OEM OS is married to the mobo, and unless the MS magisterium makes an exception then you cannot legally transfer and activate your Windows to another PC. But you can if your Windows is on retail channel as they told me to my surprise that mine was, having upgraded from XP to W.8 for $27 with a rebate, and then got the free upgrade to 8.1 and from there the free upgrade to W/10 Pro, past 3 computers. Praise God.