Microsoft has hinted at the possibility of delaying Windows Vista if it does not meet quality expectations.

Microsoft’s Jim Allchin – the man most associated with the development of the operating system - said he still expected Vista to ship at the of the year, about the same time he was due to retire, but could not rule out if being delayed.

"Where we sit today, things are going according to plan, and we’re feeling very good," Microsoft's Co-President of the Platforms, Products & Services Division said during an interview in San Francisco.

"But I always like to preface that as I did with Windows 2000, Windows XP: quality is the thing that will dictate if we’re ready to go. So if we have any problems in quality, I'll slip this product. It's the thing that is at the top of my mind."

Microsoft will release a feature-complete test version of Window Vista this quarter as planned, a move in line with the company's aim to produce the highest-quality release of Windows ever by the time it ships, he said. Microsoft expects Vista to be available on computers in time for the major holidays in the U.S., which begin at the end of November.

Microsoft has completed internal development of Vista and has no plans to add new features once the next Vista test release, called a Community Technology Preview (CTP), comes out sometime before March.

Allchin would not give a more specific time frame than this calendar quarter for when the full-featured Vista CTP will be out, though some Microsoft-watchers have blogged that it will drop on Feb. 21.

Microsoft has been releasing CTPs, or interim builds, of Windows Vista since September in an attempt to get feedback on the product earlier and more often than any previous Windows releases. By getting a feature-complete version of the product into the hands of beta testers so soon, Allchin said the company can focus now until its release on what has been its top priority for the product -- its quality.

"In the past... it wasn’t uncommon for us to add a pre-planned feature after beta 2, before Release Candidate Zero," he said. "Now we said we’re not doing that - the features are in, we’re just going to work on quality, quality, quality until we ship this product."

Microsoft has often been criticised in the past for offering first versions of new products and major updates that have as many bugs and inconsistencies as beta releases. Allchin and Microsoft are hoping to avoid that kind of user experience with Windows Vista.

"We want to make sure we drive the quality up very high," he said. "When we do something like Windows that’s literally going to [have] hundreds of millions of users using it, we want to build the highest-quality piece of software we can within a reasonable time frame. But at a certain point we make a determination: is this good enough for hundreds of millions or not? And if you rush something like that, then you end up harming everyone - our partners, us, our customers, so it has to be top of line."

In fact, the quality of the final version of Windows Vista is what inspired the entire CTP process, Allchin said. Whereas in traditional Microsoft product cycles, software would have two beta test releases with quiet periods in between them before the product would ship, Vista has been in the midst of a three-phase beta 2 process that began with a CTP code drop in December and will end with another CTP release in the second calendar quarter of 2006, he said.

Microsoft also plans to widen the beta testing pool over the next two CTP releases. By the final beta 2 phase release in the second quarter, several million users will likely have tested Windows Vista, and Microsoft plans to take their feedback very seriously before it makes the final version of the product available, Allchin said.