Believe it or not, one of the fastest, most robust, and powerful multitasking OSes is available for free. Linux can be downloaded for free or be purchased on CD-ROM for a small service charge. A handful of companies distribute Linux including Red Hat, Debian, Caldera, and many others. Linux is also possibly available for more hardware combinations than any other OS (with the possible exception of NetBSD. Supported processors include: Alpha, PowerPC, SPARC, x86, and 68xx. Most processors currently not supported are currently works-in-progress or even available in beta. For example, work is currently underway to provide support for PA-RISC, 65xx, StrongARM, and Z80. People have even successfully gotten Linux working on PDAs. As you may have guessed, Linux can be made quite lightweight. Linux is a variant of UNIX and as such, most of the traditional UNIX software will run on Linux. This especially includes the GNU software, most of which comes with the majority of Linux distributions. Fast, reliable, stable, and inexpensive, Linux is popular with ISPs, software developers, and home hobbyists alike.