Lets be HONEST here... Yes, I know that is difficult for some:
How many of those supposedly “1 in 5” macs are actually “INFECTED” vs. those who happen to have some file sitting in an email that some infected Windows user sent (intentionally or accidentally or unknowingly) to them. That file carries a worm/virus/trojan that has not actually infected that Mac... nor will/can it unless executed in a Windows environment.
If that Mac user never forwards that file/email to someone else - it isn’t an issue.
As far as the whole thumb drive or other file sharing methods being a danger to others - only if the Mac users were using the Windows environment and transferring files from within that environment. But notice the important part of that - WINDOWS environment.
So your statement that “Mac users may want to consider running Windows 7 to secure their machines.” then makes no sense - as it is the very Windows environment that is at issue and the vector of infection and/or distribution of those nasties.
I was referring to the 2.7% OSX malware rate. When compared to the windows 7 malware rate (as stated in one of the links above) is only 0.4%.
So win 7 has less malware attached than OSX does. Which is quite remarkable if you consider that Win7 has a much larger target space for the malware creators to target.