Is Windows Losing Ground?

Rimbo asks: "I work for a small company developing wireless mesh networks to (among other things) give broadband access to large areas where a single access point can't cover the whole place. Since we're small, we made the mesh networking application for Windows, intending to support other platforms later. To our surprise, our first beta site complained: 'Most of our residents use Apples.' Has anyone else experienced anything similar? Is Windows losing its dominance to the point where small shops must consider multiple OS support to get business, either through Java, 'web services,' or cross-platform toolkits like Qt?" With the number of IE vulnerabilities, macro viruses, exploits and other such annoyances over the years, is this really that surprising?