The advert was headed "Weighing the cost of Linux vs. Windows? Let's review the facts." It then displayed a graph that compared the cost per Megabit per second of "One Linux image running on two z900 mainframe CPUs" with "One Windows Server 2003 image running on two 900 MHz Intel Xeon CPUs".
According to the ASA, the advert then claimed that in a study audited by analysts META Group, "Linux was found to be over 10 times more expensive than Windows," and the "IBM z900 mainframe running Linux is much less capable and vastly more expensive than Windows Server 2003 as a platform for server consolidation".
The ASA received objections to the advert, claiming that the two operating systems had been run on different hardware and it was therefore not a like for like comparison.
After an investigation, and specialist advice, the ASA agreed, although it did note that the study had been audited, that it was a fair comparison of the systems on different hardware, and that Microsoft had intended the advert to compare "competing file serving set-ups that met the same needs and had the same function".
But the ASA had other concerns. The measurements for Linux had been performed on an IBM zSeries, which it noted was more expensive and did not perform as well as other IBM Series; and the advertisement implied that running a Linux system was, in general, 10 times more expensive than running a Windows operating system.
"It would have been possible to compare the two operating systems on the same hardware," noted the ASA, which felt that readers would infer from the advert that the study related to a comparison of operating systems only.
Microsoft Ltd. was told to change the advert and to seek advice over the content of future adverts from the Committee of Advertising Practices' Copy Advice Team.