This is a great idea. It will essentially make all Win 8 PCs into Xbox platforms. Everyone who buys a Windows 8 computer will be able to buy Xbox games and play them without having to worry about compatibility issues. Sure they won't be as graphically spectacular as games made specifically for PC, but most people don't care about graphics and Xbox games look good enough anyway.
The only downside I can see is that some lazy developers will stop doing ports and just make Xbox games and figure PC gamers will just use the Windows 8 Xbox mode to play. Not that big of deal, but I'm sure PC elitist will throw a fit over it instead of enjoying all the games they couldn't play without buying an Xbox.
It's going to be tough for Sony to compete with the Xbox brand if even their own Vaio computers run Xbox games.
This probably means that the next Xbox will be even more PC like and will probably run on a special version of Win8.
