7 used rather small border radius and on was done through the added window border/non client area, not chopped out of the window like today's UX. It was also trivially easy to adjust that to make it as tight as XP's 2-3px so if you really didn't care for it they would go away. For buttons in dialogs the radius was the same size as the embossed effect in earlier windows version.
Vista and 7 rounded things out but they sacrificed very little usable area in the application and could be adjusted to taste. Both Apple and MSFT took the stance that this was too much user control.
