Microsoft is preparing to launch the next generation of its Windows operating system by 2009. 

Ben Fathi, corporate vice president of development at Microsoft, said at the RSA Security conference in San Francisco last week that the next Windows could take two and a half years to build, putting the final release at the end of 2009.

The launch could put Microsoft back on a release schedule that would see a major operating system launch every other year.

The company previously released new operating systems on a biennial basis, but took more than five years to develop Windows Vista.

Vista was delayed in part because Microsoft pulled engineering resources off the project to work on Windows XP Service Pack 2, an update that overhauled the operating system's security after a slew of attacks against the software.

Fathi suggested that the next version of Windows would contain some of the features that the company stripped from Windows Vista.

Microsoft pulled improvements including a new file system dubbed WinFS, the UEFI Bios replacement and a set of advanced security features from Vista to prevent further product delays. 

The company is planning to add support for UEFI through a future update. Instead of implementing its new WinFS file system in its desktop operating system, Microsoft plans to integrate pieces of the technology into the SQL Server database, ActiveX Data Objects and other Microsoft products. 

Microsoft has not spoken recently about what is left of its Next Generation Secure Computing Base strategy, which envisioned a bolted down, compartmentalised security structure that would automatically contain attacks.

Kevin Kutz, director of the Windows Client at Microsoft, said in an emailed statement that the company is not yet ready to provide guidance about the next Windows version.

Microsoft has scheduled a Professional Developer Conference in Los Angeles this Autumn. 

The events for software developers occur only in years when Microsoft feels it has something new to talk about, and typically cover upcoming Windows versions.

Further details about the next Windows version also could be provided at the Windows Hardware Engineering Conference this Spring.