No, the reason Windows has more security threats is because any account that has admin privileges can do ANYTHING. You don't need a password to move or delete files or just completely trash the system. Meaning that any virus that finds itself on the system can just go hog wild.
Classic Mac OS was the same way and it had viruses just like Windows. OS X, however, does not allow the Admin accounts to do just anything and the things they can do require a password. For a true virus to be successful on OS X it needs to find a way to do it's damage without a password. However, even then it's not a guarantee. The trojan that was going around for OS X a couple months ago prompted you for your password and when you added it the only thing it could do was delete files from your user account; the rest of the system was untouchable.
Classic Mac OS was the same way and it had viruses just like Windows. OS X, however, does not allow the Admin accounts to do just anything and the things they can do require a password. For a true virus to be successful on OS X it needs to find a way to do it's damage without a password. However, even then it's not a guarantee. The trojan that was going around for OS X a couple months ago prompted you for your password and when you added it the only thing it could do was delete files from your user account; the rest of the system was untouchable.






