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The company is hosting The New Efficiency launch events across 25 US cities between September 28 and November 9 of this year for Windows 7, Windows Server 2008 R2, and Exchange 2010. Attendees will receive a free copy of Windows 7 Professional. Granted, that doesn't consider travel costs but registration and entry to the event is absolutely free.
Have a look at the event dates, times and locations at Ars Technica.