I wouldn't say that Mac's don't benefit from a Anti-Virus, but most viruses are targeted at the windows operating system these days. For a while though Macs have been based on Intel processors, so I think it might be possible some might make "cross-platform" viruses. Personally if I had a mac I wouldn't install an AV on it.
I don't have a Mac myself but I haven't heard any "regret" stories (well, not counting perhaps maybe if they really couldn't afford it, macs are generally more expensive then PCs).
Our resident Mac Guru Socrates will hopefully be able to flesh out anything I miss or correct me if I give any false information. I'm not 100% on their policies, but I believe they have excellent support policies with their products, so if you do have a problem with the mac they'll be glad to help.
I have to agree with the agree-ability of the personnel in mac stores, they actually try to sell you what you need, from what I hear, rather then, say, best buy, where I've heard people getting coerced into buying printers because the "computer won't work without one".
Personally I'm a PC person, I haven't had any issues with them that I couldn't resolve. But unlike many other PC users I'm quite open-minded to the Macintosh. it's definitely an elegant system. Personally I simply don't have a deep enough wallet for it and really like to tinker with the insides of my PCs to add and remove functionality.
Thanks, BC.
BC makes a good comment about antivirus- it's not that macs can't get a virus, it's just really rare.
I've been using macs now for 5 years and I haven't used antivirus at all. I also have had no problems with spyware or malware.
I think the bottom line is that in the future antivirus may be necessary, but for 99% of mac users, you don't have to worry about a virus today.
That being said, I used to work at an Apple Store doing the "one-to-one" training, and it is definitely worth it's money. For $99 (you have to buy it when you get a mac, now) they give you one hour training sessions every week for a year. It beats the heck outta any class or other training you can get, quality and price wise.
Apple has been rated #1 in customer support as well, and I can tell you from being a PC guy switching to Mac, it's a very enjoyable and easy switch.
Another plus is that the Apple Employees do not get paid on commission, so if you go into the store and ask them what to buy, they will help you find something that best suits your needs.
Macs now can even run windows, so if you have an odd program here or there that needs to be run on windows, you can install windows on your mac and run that application (though you need to purchase or have a copy of Windows to install).
If you have any more questions I'd be glad to answer them. Being a switcher myself I can tell you with full honesty that the leap to Mac is worth it. I used to hate macs up until 5 years ago (when I finally caved and decided to give OS X a try).
Cheers!