Wallent said one of the things he was tasked to look at was the two conflicting views about the time taken with Vista, from those who felt it took too longincluding CEO Steve Ballmer, who in July said that Microsoft would never take as long to ship another version of Windows&151;to many testers who, even late in the game, were saying that the code was buggy and not yet ready. One of the biggest differences between Vista and XP is that Vista was a far more ambitious project than XP had been and required a lot more development time, he said, pointing to the fact that XP had taken 115 days from the time that project started to reach Beta 1, while Vista had taken a year from the time that Microsoft had done the Longhorn reset in August 2004 to when it hit the first beta.What is the business case for upgrading to Vista? Click here to read more."Vista also had a lot more features and functionality and we were way more ambitious with what was going to be included there, so these metrics were not bad from a time perspective. It also took about twice as long for Vista to go from Beta 1 to Beta 2," Wallent said. Asked exactly when development work had started on Vista, Wallent said different teams had started working on this at different times. The Avalon team had started building the new framework in late 2000, while the DirectX team had also started developing the new driver model in that same timeframe. "So some teams started quite some time ago and have been working steadily since then. Some started before Windows XP SP2 was released, and others afterwards," he noted. Another significant difference between XP and Vista was that the beta distribution for XP happened almost exclusively through CDs, meaning these had to be shipped before feedback could be received. "We shipped about 500,000 CDs between all the XP betas," he said, adding that there had been some 2.25 million beta software downloads for Vista. Click here to read more about how Microsoft has called developers to Vista. Microsoft has also deployed more than 61,000 Vista desktops internally, compared with just 20,000 on XP, he said. When Microsoft thought about reliability, it included things like how often the product crashed, hung or got a blue screen, he said, adding that the company had also developed automated tools to scan and catch code errors, which was extensively used in Vista. It also did a lot of user testing, where a set of people ran a particular build for two weeks and Microsoft watched how many crashes, hangs and blue screens they got on that build. Microsoft has a scale where, if a user encountered one or none of these, its considered an "excellent" experience; if they had two or three its considered a "good" experience; and if they got four or more its considered a "poor" experience. "We improved by some 50 percent in Vista the excellent experience people had with XP. We also subjected the code to extensive and rigorous stress tests and so all the data that we have around reliability says that all the new code we wrote, plus the legacy code already in there from XP, is more reliable than ever before," Wallent said. Now that Vista has gone gold, the engineering team is looking at the backlog of issues, considering the new features they want to write, and thinking about and starting to plan for the next version of Windows, he said, although "that work has been going on for a couple of months now." Check out eWEEK.coms for Microsoft and Windows news, views and analysis.