I suppose if they want people to upgrade from old 360Fats to 360Slims, they'll want the same HDD to just plug in. How is the current drive housed? Is it possible to remove the HDD, or have they locked it in good and tight? A split HDD as you describe doesn't make sense to me as it's pandering to two different SKUs, where clearly the Fats will get dropped. At that point, MS's position can be 'if you haven't got an HDD now, you'll have to buy one quick from our remaining stock, or otherwise get a shiny new Slim'. The same happened with PS2 networking. The PS2Slim saw an end to the network adaptor for PS2Fats.