On its site, Microsoft posted a note saying "The Windows 7 Beta is now available for download." The Windows 7 site lists a where the beta can be downloaded.

On Friday, Microsoft struggled to keep its Web site online as users overloaded the company's servers. Microsoft's main Web site and the download page were often unreachable.

"Due to very heavy traffic we're seeing as a result of interest in the Windows 7 Beta, we are adding some additional infrastructure support to the Microsoft.com properties before we post the public beta," the company said on its official Windows blog Friday.

At the keynote for the Consumer Electronics Show in Las Vegas Wednesday, Microsoft CEO Steve Ballmer said Friday would be the date for beta rollout.

Company officials said activation keys for the code would be capped at 2.5 million, but users who try the beta after that limit is reached will be able to trial it for at least 30 days.