Software companies opening the source code of their applications on the Internet may seem like a car manufacturer opening up its assembly line and allowing the general public to make changes to its latest model.

However, open source has gained much popularity and publicity because of the Linux revolution, and its free and seemingly open and anarchical nature.

A recent survey by Forrester Research claims open source standards will completely reshape the software industry by 2004.

The report predicts all traditional software vendors will need to change their proprietary business models to open source ones, or drastically lower the price of enterprise application licences.

Forrester claims that Microsoft will be hit hardest. Forrester analysts say the company's business model will clash so severely with the new open source-fueled development and distribution models that the company's market share will shrink for the first time in its history.

Mr Fiachra O Marcaigh, operations editor at online.ie, says that Forrester's claims seem to represent an extreme scenario. He believes Linux will give Microsoft a run for its money, and the revelations from internal memos in the antitrust case show that Microsoft is worried about it.

Mr O Marcaigh said the advantage for companies in opening the source code of applications was that it offered them access to large-scale bug-testing. In many cases, the companies could not employ enough people to do this themselves.

He believes that one of the reasons computer programmers or software developers devote time to working on open source code is to build a reputation for themselves.

Linux's advent has formed a new business model, with distributors of the operating system, such as Red Hat, not making money out of actually distributing the software but out of technical support for their customers.

Even China is turning to Linux because of the Chinese government's fears of overdependence on Microsoft's Windows operating system.

Mr Kieran McDonnell, dot.com and application service provision manager at Microsoft Ireland, says: "There are always competitive threats and we welcome them."

He says Linux is a development-driven rather than a market-driven operating system, whereas Microsoft is investing $3 billion (€3.38 billion) on developing and improving software for its clients in the market.

Mr McDonnell said that, even though open-source software was developed from the same code base, the different versions developed by different distributors and people meant that it could be difficult to provide technical support for such software because of the myriad versions available.

In contrast, he says that Microsoft's applications are the same the world over. Although Linux has been confined in general to servers, moves are afoot in the mass market to finally compete directly with Microsoft's Office suite of applications for the personal computer.

The Gnome foundation, which has the support of IBM, Compaq, Hewlett-Packard and Sun Microsystems among others, is to develop a unified desktop user interface and a set of productivity applications intended to compete as a free alternative to Microsoft Office.

Gnome software has been gaining popularity among both Linux and Unix communities as a way to offer a common software development environment for programmers.

In a major step forward for Linux software, IBM has announced that it will begin selling computers bundled with software from Red Hat.

However, money managers have not been convinced of extent of the future of Linux. While there was large investment in the initial flotations of Linux-associated companies such as VA Linux Systems, which gained almost 700 per cent on its first day of trading, confidence in such valuations seems to be waning.

A survey by Morningstar showed that, out of several thousand mutual funds in the United States, only 24 now hold the stock, while 35 hold Red Hat.

Investors seem to be questioning how much money companies can make selling services and products around a free operating system, and Mr McDonnell says such business models are neither well-defined nor mature.

One of the criticisms of Linux as the leading open-source software is that its installation has been far from straightforward compared to the easy click and install system of Microsoft.

However, programmers now say that more recent versions, such as Mandrake, have made this more straightforward.

Linux has made its biggest impact in the server market, the powerful computers that drive technology networks, taking around a quarter of the business. The report sees that, whatever bite open-source software takes out of Microsoft's market share, the open approach is here to stay.