With the release of its first Linux laptop last week, Hewlett-Packard predicts this year the free operating system will unseat the Mac as the No. 2 desktop operating system behind Windows. Indeed, some analysts say Linux displaced the Mac as the leading alternative in 2003. Today’s the Day. But the Mac hasn’t been relegated to third just yet. While Linux machines are shipping in ever greater numbers, especially to giant markets like China, the vast majority are stripped of Linux in favor of pirate copies of Windows, experts say.