Microsoft Tuesday shipped Vista SP1 RC to select testers and said it would make the service pack publicly available next week. The SP1 release candidate is available on Microsoft Connect, and on Thursday it will be available to MSDN and TechNet subscribers. Next week, the general public will get access via Microsoft’s Download Center.

Microsoft said that with SP1 available to hundreds of millions of customers, the company is assured of extensive feedback.

“We also have information to share with IT professionals and system administrators regarding final plans for SP1: We're on track to complete and release SP1 in the first quarter of 2008,” wrote Nick White, Vista product manager, on the Vista Team Blog. 

White also said IT shops using Windows Update but postponing SP1 upgrades can download a “blocker patch” that prevents installation of SP1. The patch will be available starting Dec. 6 on Microsoft’s TechNet Web site.

On Nov. 14, Microsoft made Windows Vista SP1 RC Preview available to 15,000 testers as part of its private beta program. Microsoft hopes to align SP1’s availability with Windows Server 2008, which Microsoft hopes to ship on or before its Feb. 27, 2008, launch event in Los Angeles. Also on Tuesday, Microsoft shipped Windows Server 2008 RC1.

Microsoft officials said the Vista SP1 RC Preview incorporates feedback from users who have been part of the beta program
that began in September. The new features include changes that streamline setup and installation. The preview also includes all previously released updates since RTM: performance and reliability improvements, such as file copy, network browsing and improved response time to resume from sleep; as well as changes to administration features, including changes to BitLocker that allow encryption for multiple volumes.

Over the years, SP1 versions of Microsoft products have become a traditional milestone that some corporate users wait for before they even consider rolling out the software. Uptake of Vista has been slow by corporate users, many of whom have standardized on Windows XP and are reluctant to undertake another migration.

A study by Forrester Research shows that 52% of respondents have no plans to roll out Vista or don’t know when they might do it. The study shows 11% don’t plan to start a rollout until 2009 and another 6% are waiting until 2010.