Microsoft has finally confirmed that there will be a third service pack for Windows XP, nearly a week after the news broke and two days after a version of it appeared on the Web.

The company declined to release further details, but said that Windows XP Service Pack 3 (SP3) will be available after the shipment of Windows Vista, the next version of the client OS. Vista is scheduled to be available at the end of 2006.

"Right now, Vista is our priority," Michael Burk, product manager for Windows Vista at Microsoft, said in a statement. "We'll have more information to share after Vista ships."

News leaked that there would be a third service pack for Windows XP last week when Microsoft France security director Bernard Ourghanlian confirmed one would appear after Windows Vista. However, Microsoft then insisted the company had not decided whether or not to release a third service pack for XP.

Microsoft released the most recent Windows XP service pack, SP2, in August 2004. The service pack was one of the most significant updates to the Windows OS Microsoft ever produced, and it included a host of features to make Windows more secure.

A preview of what may be included in Windows XP SP3 appeared at software download site The Hotfix. Ethan Allen, the creator and administrator of The Hotfix, said Wednesday he put together the preview pack from software updates he received from an internal Microsoft source.