As my Sunday-school teacher was keen to say, "You shall know the truth, and the truth shall make you mad." Of course, had he become an IT manager he would have learned that finding the truth is not always easy, especially when considering operating systems, integration and the wonderful world of Microsoft marketing.

He might, for instance, have had a few difficulties in understanding Microsoft's new "Just the Facts" advertising campaign, which the company says will debunk common myths about open-source software.

It's refreshing to see Microsoft has finally acknowledged Linux as a direct competitor, but it's unfortunate that marketing campaigns are rarely confined to factual content. For example, Microsoft's earlier "Information at your fingertips" slogan was more goal than a reality.

This time Microsoft is proudly touting telecoms giant NTL as a UK firm that chose Microsoft Windows over Linux as the operating system for its customer billing system.

The story goes that NTL has consolidated 28 Risc Unix systems into one new Windows system. As NTL has three million customers in its database, we are supposed to infer that Linux is simply not suitable for big business.

Well, I wouldn't run a three-million-row customer billing database on Linux and MySQL either. MySQL is great for many things, but its reputed strengths don't include distributed transactional systems. I would consider using Oracle on Linux, but I'd probably find it more expensive than a Windows solution. It seems to me that NTL chose Microsoft in preference to Oracle, not Linux.

The Microsoft campaign also includes some questionable claims about security. Microsoft says that, at some point in time, there were more vulnerabilities in Linux than in Windows 2003; but nobody could tell me the date.

The real drawbacks of Windows are its restrictive licensing terms and endless security flaws. In terms of licensing, most IT managers are not looking for a cost-free operating system. But the cost of adding an extra Linux server is virtually nothing, whereas the cost of adding a new Windows server probably represents another significant and recurring budget item.

When it comes to security flaws, the problem seems to be that some vulnerabilities are impossible to address, and this comes straight from the horse's mouth.

Microsoft's group vice-president for platforms, Jim Allchin, testified in May 2002 that Microsoft's Message Queue software contained a coding mistake that would threaten the security of enterprise systems using it if it were ever disclosed.

In addition, IT managers seem to prefer single-function devices to vastly powerful servers running multiple applications. Linux lends itself to the single-function role extremely easily, whereas it takes a continental antitrust lawsuit to get Microsoft to remove some of the irrelevant functions from its server operating system.