Until recently you'd have been correct. I work for a large company which has always exclusively used Windows desktops (apart from some 'creative' people who had Macs for design or video). It was extremely rare to see a Mac anywhere. But in the last year or so, I'm starting to see them in large numbers, and on the desks of business people and software developers. In fact, there are now whole offices full of Macs, where once would have been Windows PCs.
A few weeks ago, I was at a software development conference, and more than half of the geeks there (and it was almost exclusively geeks) had Macbook Pros or Airs. They outnumbered Windows and Linux laptops combined. I was lugging around a heavy HP laptop (running Mint) and was really starting to see the appeal of the lightweight Air.
From what I've observed recently, Macs are making very strong headway into the traditional PC market.