Free software is great, and corporate America loves it. It's often high-quality stuff that can be downloaded free off the Internet and then copied at will. It's versatile - it can be customized to perform almost any large-scale computing task - and it's blessedly crash-resistant. A broad community of developers, from individuals to large companies like IBM, is constantly working to improve it and introduce new features. No wonder the business world has embraced it so enthusiastically: More than half the companies in the Fortune 500 are thought to be using the free operating system Linux in their data centers....