I highly doubt they would run Windows 8 on it. While they [i]have[/i] been making a conscious effort to make their PC, Xbox, and Mobile OS's as similar and unified as possible, running a regular windows operating system is a bad idea. They've made sure to draw a distinction in the past between their pc and console line, and they probably still want to keep these two things separate. The new xbox would probably run a similar OS to what the 360 currently has, and it will continue to appear similar to the Windows 8 metro interface, but running a pc OS on console hardware is a bad idea in the long run. Windows 8 would use up too much of the console's resources, and they can't expect Windows 8 to last the expected 10-year lifespan of this coming generation of consoles. As for the new Xbox being backwards compatible, it's possible that it would ship with the 360 hardware inside, but it would bring the price of the console up too high to be priced competitively with the PS4, so I don't see that happening, unfortunately.