Microsoft has made the Windows 7 Release Candidate available for FREE download and FREE USE FOR 13 MONTHS!
….The Windows 7 RC will run normally with your product key until 1 March 2010. Then, between 1 March 2010 and 1 June 2010, it will limit you to sessions of no more than two hours at a time. Effective 1 June 2010, your Windows 7 RC installation will shut down and refuse to operate until you pay Microsoft a ransom (still no word on what Windwos 7 is going to cost).
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Note that this is "free" for one year, but then you must pay Microsoft some undetermined (and probably large) amount of money to continue using the operating system. (Or, if you remember in time, you could re-install your previous operating system.)
This doesn't quite count as "free" in my book. I'll stick with what I have.
PS: It's like the joke that ends: "First prize is a new Microsoft product. Second prize is two of them."