After several delays, it appears that Microsoft may get the next version of its Windows client operating system to customers according to its current schedule.

The company has made Windows Vista Release Candidate 1 (RC1) available, which means the OS is in its final round of bug fixes and tweaks before it will be ready for release to the general public.

Windows Vista RC1 is already available to TechBeta and Technology Adoption Program (TAP) program subscribers, but MSDN (Microsoft Developer Network) and TechNet subscribers won't get the OS until next week, Microsoft said.

Microsoft has said since March that Vista will be available to business users in November and consumers in January 2007.

With the last major upgrade to Windows, Windows XP, it was about two months between RC1 and the product's release to manufacturing. If Vista follows a similar schedule the release to manufacturing - and a release to business customers - could happen as soon as early November.

OEMs (original equipment manufacturers) typically need about six weeks to get the OS installed and tested on PCs before putting those machines on the market. If Windows Vista makes it to manufacturing by the end of November, it could hit its January release date for consumers.

Online retailer is already taking pre-orders for Vista, and has listed availability of the OS as 30 January 2007 on its website.

In a letter to TechBeta subscribers, Jim Allchin, Microsoft co-president of the Platforms and Services Group, thanked them for their support and feedback, and mentioned several improvements to the OS that have been made since Beta 2 was released in May.

"We've made some UI [user interface] adjustments, added more device drivers and enhanced performance," Allchin wrote in the letter. He added that Microsoft will continue to work on Vista's "application compatibility, as well as fit and finish" until its release to manufacturing, which is yet to be determined.

Allchin also advised independent software vendors to use RC1 to certify applications to run on Windows Vista, and asked for more feedback from testers to improve the OS before its final release.

"Windows Vista is going to touch hundreds of millions of lives all around the world," he wrote. "Thanks for everything you're doing to help us give them the best experience possible."