Don't forget the rumors that MS is planning on releasing three verisons of the Xbox 2. One without the harddrive, one with and that's basicly an entry level PC that has a wireless keyboard, mouse, and controller, CD burner, and run Windows.
Of as everyone knows, "Microsoft doesn’t comment on rumors.”
As for backwards compatiblity and MS changing the processor on their next console... A company by the name of Transitive Corp. has unveiled system called QuickTransit. In a nutshell they're saying their system would allow any one platform to emulate and play software of another (think Xbox and Xbox 2). Supposedly "QuickTransit allows translated applications to run faster on new hardware than it did on the original platform, thanks to the speed of today's machines compared with those made a decade ago."
So far neither Transitive Corp. nor MS are saying that they have any sort of agreement with each other. However I thought I'd throw this in here as just something else to think about.
http://www.xbox-scene.com/xbox1data/...pVbBjCTkhd.php
http://www.transitive.com/gameing_oem.htm (Company's site)