The launch of the consumer version of Windows Vista, Microsoft Corp.'s new operating system, could be pushed back past the stated January launch date, Microsoft Chief Executive Officer Steve Ballmer said Wednesday.

The operating system was due to be launched this year but in March the company said it wouldn't get broad release until January 2007. Ballmer said Wednesday that the planned January launch may slip further based on feedback from a beta release program and the product road-maps of hardware vendors.

"We think we are on track for shipping early in the year. We've talked about the month, but we get a chance to critically assess all of the feedback we'll get from this beta release then confirm or move [the launch date] a few weeks," he said at a news conference in Tokyo.

Microsoft launched the second beta version of Windows Vista on Tuesday at the Windows Hardware Engineering Conference (WinHEC) in Seattle.

"We put the beta out today ... so we should start getting feedback right away," said Ballmer.

"The other thing, frankly, which we are discussing with NEC and other hardware partners is when would they really like it -- early January, late January, February -- so it depends on when the next roll-over, the next turn of the machine cycle will be and that would be the best time to ship it based on beta feedback," he said.

Timing the launch of the operating system with the product road-maps of PC makers is important, said Ballmer. Microsoft delayed the Vista launch from November to January to avoid putting the product out during the year-end sales season when a change in PC line-ups and operating systems could cause problems for vendors.