Microsoft Corp. released on Friday the final test version of its upcoming Windows operating system and said the launch for the highly-anticipated upgrade is running on schedule.

Incorporating feedback from earlier test releases, the world’s largest software maker said it distributed Windows Vista Release Candidate 2, or RC2, for its testers to try.

“Microsoft expects the RC2 build to be the last interim release before the product is released to manufacturing,” the company said.

Earlier this week, Goldman Sachs analyst Rick Sherlund said Microsoft will most likely ship Vista on time and distribute RC2 this week or next week, indicating that the Windows upgrade will be available for business customers in November and retail PCs by late January.

Microsoft said it continues to target that schedule for Vista, but said the final delivery date will depend on the product’s quality.

Windows Vista, already five years in the making, has been postponed by Microsoft several times and some industry analysts have speculated that the world’s largest software maker will again be forced to push back its release dates.

Microsoft Windows sits on more than 90 percent of the world’s personal computers and the Windows business accounts for about 30 percent of the company’s $44 billion in revenue.