A growing number of Linux users have tried just that. These users roll their own operating systems. They don't need Microsoft (MSFT)'s. So they'd like to return their copy of Windows and receive the promised refund.

It's month four of the government's antitrust case against Microsoft, and as anyone close to the case knows, the issues are difficult.

But next Monday, users of alternative operating systems - BeOS, Linux or OS/2 - will rally at various Microsoft offices to begin a different sort of campaign. They will demand what the license promises - a refund to those who don't want Windows. And unlike the government's top-down antitrust suit, the issues in this bottom-up movement seem refreshingly clear.

Microsoft is taking something of a hit for the offer, which seems a bit unfair. As of this writing, at least, the company has not denied the plain meaning of the license. Spokesman Adam Sohn suggests that users must approach "manufacturers."

And so many have. The LinuxMall page (www.linuxmall.com/refund/) features extensive reports of the struggles users have had with various manufacturers. Some have become legendary. The saga concerning Geoffrey Bennett in Australia began about a year ago, when he requested his refund from Toshiba (TOSBF). Toshiba at first said no, telling Bennett he could accept the machine with Windows or return the machine. But that, Bennett rightly said, is not what the contract promises. The contract says that he could return the OS, not the machine.

After a few months of bickering, Toshiba got the point. In August, Bennett received a check for $70 for the unused OS. Others have been less lucky (one story says Toshiba's promised refund price was $5). Some have been more lucky (another story reports Dell (DELL) offered $199).

The power of this campaign is growing, although there is little reason to think it will displace Windows anytime soon. Linux is not for everyone, or at least not yet, and the BeOS is cute but lonely.

But my point is not about displacing Windows. My point is about the power of contracts. There has been a lot of resistance among lawyers to shrink-wrapped agreements. Contracts are supposed to be deals on equal terms, where both sides have a chance to agree. Lawyers have been skeptical that these long-winded legal documents (redundant, I know) are really deals between equals.

I have been one of these skeptics. I have worried that these "click-wrap" deals would open the door for companies to slip one by consumers. And I have criticized attempts by lobbyists to quickly write a new legal code (called the UCC 2b) to validate click-wrap agreements.

But the Net continues to surprise lawyers like me. We think, "How could a consumer ever really enforce the terms of such an agreement." But the Internet shows us how. For less money than big-firm lawyers charge in an hour, a Web campaign can be born. And in less time than it takes to get to trial, that campaign can mature into something big. Thousands of people can come together to insist that the promisor do what was promised. And in the end, I suspect, the promisor, or its agents, will.

This is the best of the Net. It is the best of bottom-up governance, although of course, in the end, it is governance that relies on law - contract law. And it is the best of contract law, for it affirms the basic equality that a contract represents. When, Oliver Twist-like, Geoffrey Bennett says, "Please, sir, may I have the refund," and when Wizard of Oz-like, Toshiba blasts, "What? What refund?" contract law, Jimmy Stewart-like, responds, "Just do what you promised, however powerful you might be." This is a new phase for law, however old it might be in the law of the Net.

There is still much to worry about in click-wrap agreements. But as a critic of UCC 2b, it is only fair to give credit where credit is due. The current draft affirms the right of a refund, and would even require the licensor to pay the costs of getting the refunds. Said one lawyer on an e-mail list, "I wonder if that includes attorneys' fees."

Lawrence Lessig is the Berkman Professor of Law at Harvard Law School. E-mail him at lessig@law.harvard.edu.