"newer architecture" doesn't really mean much. Microsoft have to maintain a more rigid overall structure because they are committed to third-party binary compat

"newer architecture" doesn't really mean much. Microsoft have to maintain a more rigid overall structure because they are committed to third-party binary compatibility wrt drivers and such. As a result, major architectural shifts in things like networking or graphics (XP -> Vista) cause a lot of pain. It's a trade-off. Linux looks floppy architecturally because it can afford to be.