The more I think about it, the more I suspect that I may never have had a malware problem on my Windows partition. I used to figure that if I had Windows running longer than six months, it got malware. At least, that was my previous experience. But, that experience was based on running Windows only.
In the last 1 1/2 years since I installed my dual boot desktop, I used Windows for schoolwork, iTunes and Audible.com. I used Linux for everything else, especially random internet surfing. If I didn't have school, I'd wouldn't use Windows at all. I get it through school, as part of our materials for training. I rarely use Windows for surfing the internet, and I never went on myspace or facebook with it. Most of my mail was opened in Ubuntu, and unless I know who it's from, I don't open attachments. So, looking back, I rarely exposed Windows to potential malware.
Maybe most people who insist on using Windows should have a dual boot system. They could surf and email from Linux, and do whatever they need to for work or school in Windows. As more applications are available online, there will be less of a need for a particular operating system, be it Windows, Mac, or Linux. That's a whole 'nuther security issue itself, though.