Computerworld — Office 2010's public beta has leaked to the Web, days ahead of its anticipated roll-out next week, searches of file-sharing sites showed today.

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The 32- and 64-bit versions of the Office 2010 Beta have appeared on several peer-to-peer BitTorrent tracking sites, including Mininova.org , with the first one posted there on Tuesday. As of noon ET, the 32-bit version showed about 300 "seeders" -- the term for a computer that has a complete copy of the torrent file -- and about 150 "leechers," or computers that have downloaded only part of the complete torrent. Approximately 2,800 copies of the 646MB file had been downloaded.

Office 2010's 64-bit edition -- the upcoming suite is the first that Microsoft will produce a version specific for 64-bit versions of Windows -- boasted 150 seeders but fewer than 50 leechers. More than 1,400 copies of the 710MB file had been downloaded by mid-day.

According to Neowin.net , the Office 2010 build is tagged as 14.0.4514.1009, and requires an activation key.

Users commenting on Mininova.org confirmed that the leaked beta installs and works, although many complained that they needed a product key to activate the suite so it could be used for longer than 30 days. Several others, however, offered up workarounds to sidestep activation.

When Microsoft launched the public beta of Windows 7, and then the follow-up release candidate, it provided limited-time product activation keys to users. Presumably, the company will repeat that practice with the Office 2010 beta.

Previews of Office 2010 have leaked before official availability twice already this year. In May, a week after Microsoft announced that it would issue the Technical Preview in the summer, an early edition showed up on BitTorrent. The same thing happened in July, when the Technical Preview went public hours before Microsoft revealed the invite-only test program at its Worldwide Partner Conference (WPC).

Earlier this week, Microsoft shut down Technical Preview downloads, and told testers to expect news of the public beta next week. Microsoft will kick off its annual Professional Developers Conference (PDC) next Monday in Los Angeles, and is expected to use that forum to unveil the public beta.

Last year, Microsoft released an alpha build of Windows 7 to PDC attendees.

Microsoft has also been dropping broad hints of an impending Office 2010 public beta on its Twitter feed. "MS Office team has some exiting news to tell at PDC. This is a must attend event. Stay tuned!" Microsoft tweeted Tuesday morning.

It's unclear whether Microsoft will cap the number of Office 2010 downloads, a move that would duplicate the clumsy process last January when it launched Windows 7's public beta, or whether it will simply limit time the beta is available, which is what it did with Windows 7 release candidate.

Microsoft has, however, promised to distribute millions of copies of the Office 2010 public beta.