Thanks for the link, nontroppo. If Microsoft manages to pull this off, maybe we can all pretend Vista never happened. Point is, users don't want mere change, but improvement. And the 800-lb. gorilla in the room is legacy support, viz., "compatibility code." At some point, Microsoft has to cede it. I thought they'd do it with Vista, leaving XP for the rest of us. But it's big part of the reason Vista was so slow for new hardware (and to market).
When you do the same with the UI, though, it's painful. It's typical of Apple to say, "Take or leave it; here's the new way." But when Microsoft did the same with Office's ribbon, with no way to revert to classic toolbars, I was turned off. Same with the taskbar. I'll take functional over sexy every time.