Microsoft is keeping mum about its decision Friday to delay the release of its Xbox video game console by a week. Regardless, the postponement again puts the machine back-to-back with the U.S. introduction of Nintendo's GameCube. The Xbox will now launch Nov. 15, not Nov. 8 as originally planned. Microsoft would not cite a reason for the delay. "We looked at a lot of different factors," said James Bernard, Microsoft's main Xbox spokesman. "This turned out to be the best time to launch for us, for our partners and our customers." Microsoft is also being vague about the number of consoles it will release at launch. The software giant originally promised that 600,000 to 800,000 consoles would be available at launch, as the company hoped to avoid the shortages and frustration that accompanied the U.S. arrival of Sony's PlayStation 2 console last fall. Now Microsoft will only specify that 1 million to 1.5 million units will ship through the holiday shopping season, and that the company will be able to deliver to stores at least 100,000 new units per week after the launch.