Windows development chief James Allchin has said he was being "purposefully dramatic" in an email to Bill Gates and Steve Ballmer in which he said he would buy an Apple Mac if he wasn't a Microsoft employee.

The email, sent in 2003, outlined how development on the new Windows Vista operating system had gone astray and emerged this week at an Iowa anti-trust trial against Microsoft.

Allchin has since said that the email was a "rant" written to force a change in the way Vista was being developed. "I made the comment for effect about buying a Mac if I was not working at Microsoft," Allchin said this week. "Taken out of context, this comment could be confusing."

He went on: "This email is nearly three years old, and I was being purposefully dramatic in order to drive home a point. The point being that we needed to change and change quickly. We did: we changed dramatically the development process that was being used and we reset the Windows Vista development project in mid-2004, essentially starting over."

Allchin is the co-president of Microsoft's platform and services division and is stepping down at the end of this year as Vista nears its 30 January ship date to consumers. He has previously stated that delays in Windows Vista's arrival five years after Windows XP, rather than Microsoft's aimed-for three-year gap were due to extensive rewriting of code in order to make the OS more secure and bug-free.

Allchin was also quoted by lawyers representing Iowa consumers in their opening arguments in the case of Comes v. Microsoft as saying Microsoft had "lost sight" of customers' needs. But in a blog posting, Allchin said his comments were consistent with the "spirit of being self-critical" that "continues to flourish at Microsoft. Within Microsoft everyone considers it their duty to always put their convictions and our product quality ahead of everything else. That was the intent of my mail to Bill and Steve, and I consider it a great example of how this company can focus and do what's right for customers."

The ongoing legal fight is one of two remaining anti-trust cases at the state level from the slew of cases brought by the US government and multiple states starting in the late 1990s. Microsoft has already settled one similar class-action lawsuit brought by the state of California in 2004 for $1.1 billion.