Linux has made rapid progress in the server market, where it continues to grow despite the dot-com crash. A recent study estimated that Linux now runs 30 percent of Web servers, and companies buying Linux say that it has now conquered many of its early shortcomings, such as lack of applications and its restriction to lower-end machines.

This success has helped some Linux companies to prosper-Red Hat, which sells a distribution of Linux and which went public at the height of the dot-com frenzy, recently announced its first profitable quarter, even as competitors such as Turbolinux and VA Linux have run into difficulties. VA Linux, one of the earliest Linux companies, has said it will stop selling Linux-based hardware to focus on software and services.

Microsoft, never a friend of open source, has gone on the attack in the past few months, with executives including Bill Gates branding open source as an enemy of intellectual property and free enterprise. But there are some signs that the strategy has backfired: It has given fractious Linux leaders a cause to unite against, and has attracted criticism from legal experts, some of whom have called Microsoft's statements on open source and the GNU Public License misleading.