The main challenge facing the Big Three Linux converts now is that the world's appetite for a better operating system has been more or less satisfied. Windows 3.1, 98, 98SE and ME were terribly flawed, and made everyone yearn for something better. CP/M, NextStep, BeOS, OS/2 Warp and UNIX never answered those prayers, and neither did Apple, which controls only a sliver of the market.
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Source: The Globe and Mail