The firm announced last month that the operating system was finished, and the release to manufacturing version is being made available for early adopters and technical subscribers.
The public beta of Windows 7 will be limited to English language versions at launch, but other languages are expected to be added in October through the TechNet and MSDN pages. The operating system is on track to be released to the general public on 22 October.
Pirated copies of Windows 7 appeared briefly on file-share sites last week until Microsoft deactivated the leaked activation key, which was widely thought to have come from Lenovo. Microsoft warned potential downloaders to wait for the official release.
The final version of Windows 7 will cost £149.99, £219.99 and £229.99 for the Home Premium, Professional and Ultimate versions respectively. Upgrades from existing installations will cost between £79.99 and £199.99.
Both hardware and software versions of the operating systems are expected to be released today.
Electronics and computer chain the latest high street retailer to fall into difficulties
Incisive Media and Investec Asset Management supported fundraiser crosses Atlantic in 40 days
Alphabet's health sciences division Verily have been messing with AI algorithms