By Aidan Malley

Published: 08:00 PM EST

However well customers are taking to Windows Vista, its replacement is only in the earliest stages of development, according to a statement from Microsoft.

The Redmond, Washington-based software giant dashed hopes of an early release of Windows 7 in 2009 in an e-mail message from a company spokesperson, suggesting instead that the operating system was too far away to be ready for a commercial release next year.

"We are currently in the planning stages for Windows 7 and expect it will take approximately 3 years to develop," said the spokesperson. "The specific release date will be determined once the company meets its quality bar for release."

Microsoft also dismissed notions that it was stepping up the development process for the software. The company was "confident" that businesses appreciated Vista and justified any initial hesitation in the segment by arguing that the OS was only just entering mainstream adoption and that it was typical for only a small number of companies to become early adopters of a new Windows release.

The company sold approximately 100 million copies of Vista during 2007 but did so in a much larger market that saw sales of 269 million PCs, according to research firm IDC, indicating that most PCs shipped with Windows XP or other versions of the software released before Vista.

The estimate may place Windows 7 as far away as 2011, or four years after Vista's January 2007 launch, though Microsoft is not known to have indicated whether the three-year timeframe began this year or just after the completion of Vista.

If begun in 2008, Windows 7's development time will be only slightly shorter than for its predecessor. Vista was originally intended for a 2004 introduction but encountered major code rewrites and other delays that pushed it back three years.

By contrast, Apple released Mac OS X Jaguar, Panther, and Tiger in between Microsoft's non-server OS releases and unveiled Leopard in October of last year. The next major release of Mac OS X is due to arrive within 12 to 18 months of the Leopard, according to statements by company chief executive Steve Jobs. That would put its release sometime between late this year and the spring of 2009.