(MONEY Magazine) – One of Microsoft's biggest brands finds itself in legal jeopardy as the result of a suit filed by a tiny start-up with the unlikely name of Lindows.com. Last spring, a federal district court in Seattle turned down Microsoft's request for a preliminary injunction against the start-up, which is marketing a dirt-cheap Linux-based operating system designed to challenge Microsoft's venerable Windows franchise. Microsoft says Lindows is cashing in on a brand the software giant spent more than a billion bucks building. And the case has some wondering what's next--Boca-Cola, a refreshing soft drink for Florida retirees?

Lindows, for its part, argues in a countersuit that "windows" is a generic term for those rectangular thingies cluttering your PC screen--and thus undeserving of trademark protection. Lindows' filings, filled with references to oddball cases like Liquid Controls Corp. v. Liquid Control Corp., make the point that in the early days of the PC business, Windows-like applications were described as "windowing environments" by nearly everyone--including Microsoft. Given its own generic use of the term, "Microsoft is its own worst enemy," says Anton Hopen, a Florida lawyer following the lawsuit. The case is expected to go before a jury in April. --DAVID FUTRELLE