Microsoft has completed Windows Vista development and expects to ship it by the end of the year.

The release would coincide with the retirement of veteran Windows development leader Jim Allchin - but Allchin is willing to put off both events if Windows Vista doesn't reach a standard of quality he approves of, he confirmed on Friday.

"Where we sit today, things are going according to plan, and we're feeling very good," Allchin, Microsoft's co-president of the platforms, products and services division said. "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."

Complete Windows Vista beta ships this quarter

Microsoft will release a feature-complete test version of Window Vista this quarter as planned.

Internal development of Vista is complete. The company has no plans to add features once the next test release ships in March.

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 been criticised before 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 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."