Microsoft said it released a public trial version of Vista, the newest version of its ubiquitous Windows operating set for a full rollout in January.
"Microsoft has officially kicked off the Windows Vista Customer Preview Program (CPP), providing the broadest access yet to pre-release test versions of Windows Vista," a company spokesman said in a statement.
This test version "allows developers and IT professionals who dont have access to pre-release versions of Windows Vista through other channels to obtain the code and begin their testing."
The release is a normal part of the rollout for Windows, which is used by many software developers whose programs interact with the operating system installed on some 90 percent of personal computers worldwide.
"This broad availability of pre-release code represents a significant milestone in the development of Windows Vista and the feedback received from testers will help us further refine certain areas of the product," the company said.
Microsoft earlier this year delayed the release of Vista until January, missing the key year-end period for computer sales.
The much-heralded Vista platform will now only be launched to the public after the end-of-year holiday sales, the company's busiest sales period and a full five years after the release of its last system, Windows XP.