That is because 99.9999% of all viruses created are made to attack Windows not a MAC, why create a virus that will only affect 5 - 7% of computers sold today
Exactly. Once it becomes economically viable to attack Macs, you will see a lot more of this. If everyone has the attitude that Macs are invincible because Apple is better than Microsoft, they will be in for a rude awakening when the attack comes.
