Microsoft made Linux one of the top items on the agenda of its Worldwide Partner Conference over the weekend, complete with tips on how to demolish the open-source competition and a hands-on lab letting partners try out the operating system.

Chief executive Steve Ballmer exhorted partners to take aim at "legacy" products such as IBM's Lotus Notes and Novell's Netware, calling IBM Microsoft's No. 1 competitor. Sessions such as "Selling Against Competitive Platforms" and "Winning in the mid-market vs. Linux", however, acknowledged that Linux has emerged as the main competition for customers looking to switch away from IBM, Novell or NT4.

A talk by Mike Nash, corporate vice president of Microsoft's Security Business and Technology Unit, claimed Microsoft's progress on security in the past two years has made Windows more secure than Linux. Windows XP SP2 has had half the number of critical vulnerabilities compared with earlier versions of Windows in the nine months since SP2's release in August 2004, Nash said.

Microsoft even brought in Techstream, a small IT training firm, to run a hands-on Linux lab for partners interested in knowing more about open source. The lab allowed attendees to try out Apache and a Linux installation with the KDE desktop interface, according to a report in industry journal eWeek.

Techstream's Don Johnson reportedly said Linux is more flexible than Windows, with the trade-offs being complexity and lack of integration. While users might switch to Linux to avoid vendor lock-in, distributors such as Red Hat and Novell's Suse Linux effectively lock users in, Johnson said, since switching from them is "by no means easy".

The presence of Linux at a major Microsoft event is another sign of change in Microsoft's attitude towards open source. The company once contented itself with demonising open-source software, and particularly the GNU General Public License that governs Linux. But in recent months Microsoft has opened up to dialogue with top executives at Linux vendors and has begun regularly appearing at Linux trade shows.

These moves might seem to point to a more relaxed attitude, but open-source leaders see them as nothing more than a new tactic to help Microsoft understand its enemy.

"If Microsoft were to really try to exist in harmony (with open source developers) then they'd need to do something to adjust the controller/controllee relationship with their customers," Andrew Morton, lead maintainer for the Linux public production kernel, told Techworld.

"Open source is about giving users the freedom to understand the software, to contribute to it, to make changes which they need, to integrate it with other products. I expect that if (Microsoft) were to do anything in that area it would be contrary to shareholders' interests, so it won't be happening."