I love the virus argument. Let's explore that one. According to the stats here:
http://www.businessinsider.com/apple...s-sinks-2009-4
Apple's market share gains levelled off at a whopping 7.4%. WOW.
According to the sources quoted here:
http://en.wikipedia.org/wiki/Microsoft_Windows
Microsoft owns 91% of the OS market share.
Now lets consider motives.
Q: What is the primary motive for writing viruses and spyware?
A: To cause either chaos (viruses) or to make money (market research statistics forwarded to a central point, or via theft/fraud)
Q: Why would someone go through the trouble of writing code for these complex applications (virus/spyware) for a platform that only affects 7.4% of the market?
A: Good question. Primarily they don't.