By default, Fedora includes SELinux, which enforces security policies throughout the OS. Developed by the U.S. National Security Agency, this app does an excellent job of alerting users to potential security threats and managing user authentication. Most users will find that the biggest benefit of SELinux is its management of root user authority: The program alerts you when you've had root privileges activated for more than a few minutes, so you can minimize your exposure from this vulnerability.

For users who are already familiar with Linux, Fedora 9 is an excellent choice. Robust security features and installation options make it somewhat more versatile than Ubuntu, which offers a more streamlined (and therefore more restricted) installation. For most users, though, including millions interested in trying Linux for the first time, Fedora lacks the polish and ready-to-run simplicity of its more popular rival.

Ubuntu 8.0.4 offers a level of functionality comparable to that of Mac OS and Windows, from delivery to installation to daily use. Unfortunately, the ties that bind all Linux distributions — primarily a lack of support for major Windows- and Mac-based business, design, and gaming applications — still hold Ubuntu back from mass popularity. For users with such moderate computing needs as Web browsing, e-mail, and basic document creation, however, Hardy is a compelling option.