As Apple prepares to enter beta testing of its next major upgrade to Mac OS X - codenamed Panther - Microsoft has confirmed its own operating system road map.

Microsoft is set to introduce "Longhorn", the successor to Windows XP in 2005.

Analysts say the move will be one of the most important Windows launches for Microsoft. The release will follow a pre-beta release in October 2003, a first beta in early 2004 and a second beta in mid-2004, the company revealed.

"We will see Longhorn coming to market in 2005," said Will Poole, senior vice president for Microsoft's Windows Client division.

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.