One of the reasons I switched from Vista/XP to OSX is I got really tired of buying antivirus software that was ineffective anyway. Most virus software is behind the times, that is they usually release an update to their definitions once an exploit is found. Windows by default tends to accept any and all information to the machine so of course it is more vulnerable. The antivirus crowds have to play catch up all the time because there are just so many holes, so many infinite ways to exploit the OS.
Not too mention that every antivirus scanner worth its salt will slow your system down some. It has to, to keep up with all of the information passing through it. You are asking it to check and recheck everything you do, which is darn near impossible, without making your system crawl.
Buying a firewall does help, as it closes many of the doors left open by windows (if you want to see how many of your doors are indeed open do a google search for GRC Shields Up. It is an online scanner that tests your open windows ports) therefore easing the load on the antivirus software. So now you have two pieces of software running on your computer to prevent your system from letting itself be attacked.
Lest we forget however there is also spyware, and oh Lord, don't get me started on that subject . . .
As someone explained above, the Mac is different because it works like Linux in effect removing the possibility of being infected unaware. You cannot get a virus on mac unless you allow it to happen or basically say yeah go ahead, which is great for me. This means I no longer have to spend too much money on a product i do not want and I currently do not have any virus, firewall or spyware programs on my MacMini, and I am not afraid.
Can i be hacked? yes anyone can, but at least i am not opening the door for them to come inside
