Viruses and such?

Heres my question, Not that I can dual Boot (still PM) but for those who can. Wont Dual Booting now make your mac as fragile as your pc in some sense? Because your saving the OS on the same HD as your OSX. And we know the problem with windows and its Virus and spyware wasnt a P4 chip or an AMD chipset but the security of the OS itself.

So wouldnt you be opening up the door to getting infected and so forth now and possibly corrupting your other files and such?