If I may quote from Matthew 7:5, the King James Bible, "First cast out the beam out of thine own eye; and then shalt thou see clearly to cast out the mote out of thy brother's eye."
Window PCs has far, far more malware trouble than Macs, and I can't resist mentioning that after in twenty-years of Linux, we've not seen a real-world example of Linux malware--not counting the Android malware mess. Ironically, these latest appalling Windows malware numbers are shared in a Microsoft blog about how well SmartScreen Application Reputation is working in IE9.
In the meantime, no matter what operating system you run, and yes that includes Macs and Linux, you need to take anti-virus software and malicious Web sites seriously. Android users, for example, can't get 99.9999% of the malware out there, but their Google application sessions can still be spied on and if you're not securing your network sessions, it doesn't matter what you're running, your Web sessions can still be hi-jacked with Firesheep.
Sure, Windows, with or without IE9 has more security problems than all the other operating systems rolled together, but today network insecurity is everyone's problem.