Isn't this a tad overconfident? While you run Boot Camp or Windows using some other virtualization software, you do (and therefore the software does) have access to your Mac files. Theoretically, malware could disrupt OS X in that situation.
I don't bring this up to scare anyone, but I see an awful lot of comments here that Macs CANNOT be harmed by Windows viruses and I think some of that is whistling past the graveyard.
mt