Microsoft has announced plans to deliver Longhorn, the next version of the Windows desktop client, in 2006. But to meet this deadline, Longhorn will not include some previously announced features, such as the WinFS storage subsystem. However, other Longhorn technologies will be made available for existing versions of Windows, which could smooth the upgrade path to the next version of the operating system.

"Getting Longhorn to customers in 2006 will provide important advances in performance, security and reliability, and will help accelerate the creation of exciting new applications by developers across the industry," said Microsoft chairman Bill Gates in a statement.

The firm aims to release Longhorn to manufacturing in May or June 2006, with broad availability to customers before the end of that year.

To meet this schedule, the proposed WinFS storage subsystem will now be delivered after Longhorn is released, according to Microsoft. WinFS is an ambitious project to replace the familiar Windows file system with a database-like retrieval tool. The aim of WinFS is to make it easier to find and cross-reference information.

David Weeks, Windows product manager for Microsoft UK, said WinFS will be in beta when Longhorn ships, and will be available as an update in 2007.

Along with WinFS, Longhorn was expected to feature new web-based communication and collaboration features, codenamed Indigo, plus presentation and media features in the form of a new user interface known as Avalon. While these are still due to ship in Longhorn, Microsoft now also plans to make these features available in 2006 to customers running Windows XP and Windows Server 2003.

This move will expand opportunities for developers by enabling them to create applications that run on hundreds of millions of existing PCs, Microsoft said. It will also smooth the upgrade path to Longhorn for firms, many of which have only just moved to Windows 2000 or Windows XP. "Large customers today will not replace 50,000 desktops at one go. This will enable a migration path to Longhorn," Weeks said.

Longhorn was on Microsoft roadmaps as early as 2001, originally slated as a relatively minor release to follow Windows XP. Since then, development delays and work on Windows XP Service Pack 2 have pushed back Longhorn's release date to 2006. A server version of Longhorn is still expected to ship in 2007, Microsoft said.