Adam Abdul-Rahman wrote in with the following question: "Are Microsoft operating systems the only ones available for PCs? Are there any other ones, and how do they compare?"

This set off a few alarm bells in the PC World offices. Do we focus on Windows at the expense of other operating systems? Hmm. Is the Pope a catholic? A quick look at the Help Screen database revealed the following article count: Windows (3.x, 95, 98, NT): 299; Other operating systems: 4.

Well, we live in a Windows world. Until that changes, Windows is bound to dominate the Help Screen. But it's time we devoted more space to non-Microsoft alternatives. This section is the first in a series on Linux, the operating system that might - just might - challenge Windows in the years ahead.

In answer to your question, Adam, yes, there are other operating systems, but they have taken such a battering from the almost omnipotent Microsoft marketing machine, it's easy to overlook their existence. IBM's OS/2 is a case in point. In the early 1990s, a few industry pundits were predicting that OS/2 might stop the Microsoft juggernaut in its tracks. It didn't, of course, although OS/2 continues to have a dedicated following, especially in the financial services industry.

In 1998, a new kid arrived on the block, and it's called Linux. Actually, it's not particularly new - the OS was pioneered by a young Finnish programmer called Linus Torvalds as early as 1991 - but it has only recently caught the public imagination. (Incidentally, if you want to pronounce "Linux" with the appropriate Finnish twang, listen to Linus Torvalds' demonstration, available at www.linux.org.au/SillySounds/english.au.) Sceptics are predicting that Linux will go the way of the Tasmanian tiger (and OS/2), and they may be right, but its immediate future is bright. Some estimates put the Linux user base as high as seven million - not enough to have Microsoft executives choking on their Moet, but sufficient to send a few ripples through the industry.

As reported in last month's PC World (Linux revs up as challenger to NT, p22) industry heavyweights Intel and Netscape are buying into Linux, with substantial investments in Linux vendor Red Hat Software. And Novell is working on a Linux version of its directory services technology. Linux won't reach critical mass for a few years yet, partly because there is very little desktop productivity software available for the platform. But a number of software vendors are developing Linux applications. Corel already has a pre-release version of its WordPerfect suite that runs on Unix/Linux. This might just be enough to start a stampede.

Some industry analysts are arguing that the future of Linux as a mass market operating system depends on the success or failure of NT 5. Bill Gates once admitted that he was "betting the farm" on NT 5, and it's certainly an interesting gamble. If it succeeds, Microsoft will effectively guarantee its dominance of the OS market until well into the next century. But if the NT 5 release date recedes still further into the future, and if its zillion lines of code are crawling with the usual "version one" bugs, an OS such as Linux might begin to woo some serious corporate customers.

Linux is a variant of Unix, the operating system on which the Internet was built. But it differs from other versions of Unix (and other operating systems) in several key respects. For one thing, it's free: you can download the OS from any number of locations on the Web and it won't cost you a cent. It's also an operating system without secrets: its source code is freely available. What's more, although Linus Torvalds "gave birth" to Linux, he has never been a jealous parent. Thousands of programmers have modified the source code, improving it and adapting it to meet the requirements of different environments.

We're not suggesting that you bin your Win 95/98 CD just yet, but it's reassuring to know that you might have another choice.

This month's Linux section has sought to provide an overview of the operating system, but of course we have barely touched the surface. Next month, we will look more closely at the software - how you can use it and where you can find a version that's right for you. If you have any queries or comments about Linux, please send them to the Help Screen.

For general information about Linux, vendor sites are a good place to start:

Red Hat Software

Debian GNU/Linux

Slackware Linux

For excellent coverage of Linux in Australia, visit:

Linux Australia

IDG Communications, publisher of PC World, recently launched an online magazine devoted to Linux. Check out:

LinuxWorld