The Beta kits - the PowerMac based systems were designated Alpha kits - have a
processor and graphics chipset configuration much closer to the final hardware that will appear in Xbox 360.
Prior to E3, developers reported that a very small number of these more advanced kits had been manufactured, but it's only in recent weeks that they have begun shipping to Microsoft's development partners on a wide scale.
Microsoft received some criticism after E3 for showcasing its titles on hardware which, it claimed, only represented 25 to 30 per cent of the power of the final Xbox 360 - while Sony had more advanced development kits for the PS3, despite being at least six months further from launch.
