Re Core 2 duo desktops
My last desktop "upgrade" was to complete silence, and in CPU terms was a downgrade possibly even from Core 2 Duo. SSD + fanless Celeron J1900 Mobo in mini-ITX case may well be the last desktop PC I ever need to buy, apart from replacements after hardware failure. The are good reasons for full-spec Core-i5/i7 systems, but none that make me want one at home.
I have a tablet as well, it does all I want it to (not very much!) And a £50 Kindle with paper display, which I find the most "magical" of my devices, and a perfect replacement for a daily paper made of mashed tree.