Microsoft Corp has for the first time publicly confirmed 2005 as the release year for Longhorn, the successor to Windows XP. [

The operating system release, which analysts have said will be one of the most important Windows launches for Microsoft, will follow a pre-beta release in October, a first beta in early 2004 and a second beta in mid-2004, said Will Poole, senior vice president for Microsoft's Windows Client division, in a presentation at the company's Windows Hardware Engineering Conference (WinHEC) in New Orleans.

"We will see Longhorn coming to market in 2005," Poole said.

The shipping year for Longhorn had been a moving target; insiders first expected it to come late 2004 or early 2005, though recently most had pegged 2005 as the year for Longhorn. The pre-beta release will coincide with Microsoft's Professional Developers Conference (PDC) in Los Angeles in October, the company said.

"At PDC there will be a build suitable for hardware and software developers to start creating applications for Longhorn. The build is not meant for broad customer usage, but for developer usage," said Tom Phillips, general manager of Microsoft's Windows Hardware group.

Microsoft released a developer preview of Longhorn in March, the company said. Three alpha versions of Longhorn have leaked onto the Internet, the first surfacing late last year and the most recent leak last month. Before Longhorn comes to market, there will be some follow-on releases to existing Microsoft operating system products, Poole said. New language editions of Windows XP Media Center Edition, for example, he said. However, "the weight of the (Windows) division and the company is behind Longhorn."

A big change in Longhorn will be the new Windows Future Storage (WinFS) file system, based on SQL Server database technology and designed to give users a direct route to data, making the physical location of a file irrelevant. WinFS replaces the NTFS and FAT32 file systems used in current Windows versions.