"In order to make this date (of 2006), we've had to simplify some things, to stagger it. One of the things we're staggering is the Windows storage work," Jim Allchin, Microsoft's vice president in charge of Windows development, said in an interview with CNET News.com. "We’ll still have rapid search covering the data just as we planned."

The software maker has not had a full release of its desktop operating system since Windows XP debuted in October 2001, although the company has shipped specialized versions of the operating system, such as the Tablet PC and Media Center editions. Microsoft has also been faced with a strain on its programming resources for Longhorn, with much of the Windows development team commandeered to complete the Service Pack 2 security update to Windows XP, which Microsoft finished earlier this month.

Longhorn was originally supposed to have three major changes: a new file system, WinFS; a new graphics and presentation engine known as Avalon; and Indigo, a Web services and communication architecture.

Microsoft is making changes to all three pillars. WinFS will be available as a beta when the Longhorn release comes out as a client. Avalon and Indigo will be part of Longhorn, but also made available separately for Windows XP and Windows Server 2003.