Open source software is making in-roads into the business market, the latest survey by Forrester has found.

The company surveyed 140 large companies in North America and found that 65 of the 140 companies questioned - just under 50 percent - are using open source applications. A further 20 companies said they intend to use open source products in the next year, leaving just 55 with no plans. Perhaps crucially, half of these companies are also using open-source software for vital applications.

In terms of the most popular open-source applications, Linux leads the way (every company with open source and planning to use open source has Linux) with Apache close behind (75 percent of companies). MySQL (52 percent) and Tomcat (44 percent) come close behind them.

The reasons given for adopting open source are the same as ever - lower acquisition costs, lower total cost of ownership and greater flexibility in choosing hardware and software. In an earlier Forrester study of 290 North American companies, 69 percent listed the reduction of operating costs in 2004 as their main goal.

But whether open source software is cheaper than proprietary software is still under dispute among IT professionals. "There are plenty of costs that are buried into bringing a new piece of software into an organisation, things like integration and support," said author of the report Ted Schadler. Schadler puts the increased control that open source gives companies over their infrastructure as a main driver - they can choose the platforms they use, control security and software assets that work with the open source components, he said.

Of the 85 companies using, or planning to use, open source in the next 12 months, 39 percent use, or plan to use, scripting languages PHP, Perl or Python, while 38 percent use, or plan to use, SAMBA and Just over a fifth have deployed, or will deploy, Jboss, while 18 percent use, or will use, Struts. Additionally, 17 percent develop, or will develop, software using Eclipse.

Top concerns cited about open source, from all 140 companies surveyed, include lack of support and the availability and maturity of applications. Companies are also worried about not having workers skilled enough to support or use open source applications, the licensing costs, security and getting sued.

Schadler added that IT professionals need to teach their companies that open source is more than just free software. It's the result of the open source methodology, which is based on the scientific method - published results, peer review and modular development. "It produces high quality software and the most high quality intellectual property in the world," he said.

Before jumping into open source, Schadler recommends companies form an open source advisory committee comprised of IT professionals, developers, financiers and intellectual property lawyers to evaluate several factors: the health of a community supporting a particular product; the licensing scheme; the leadership behind the product; which vendors support and contribute to the product; and what kind of commercial support is available.

The report is available for $249 at Forrester's site here.