I am using ClamX every couple of monhs to clean Word macro-viruses from clients machines. Macs can get affected by these viruses also. They do not do any damage per se but you pass them on to other users which in turn are usually not very happy. So there´s your need for anti-virus protection on the mac.

My PC is virus-free for a year and a half now. My Mac is too, for the same period of time. Note that that's not "found and removed", that's "never had even one".

The biggest trick to not getting virii is to not be stupid. If you're exposed to virii on your home computer (workplaces are sometimes targets, so they're exempt), odds are you were being stupid somehow. That's not a guarantee, but it's very likely.

And, frankly, if the PC I'm sending files to doesn't have a virus scanner, screw 'em. There are free ones all over that are nearly as good as the biggies, there's just no excuse for not having a Windows machine without an anti-virus program.

Jailerjoe, allow me to reiterate my point that spam emails typically come from Windows PCs that have been zombified by malicious software without their owners' knowledge. Thus, even though you and I don't use Windows, we are still affected by Windows viruses.

The more Windows PCs with viruses there are, the more spam you and I get in our inboxes, and that is why we should both run ClamXav and get Windows users to switch to Firefox.

@jailerjoe:
Maybe you don't need/want an antivirus, but there are people who are forced to have Windows machines on their homes or business or have to upload windows files to servers for other people to access them. There are also cross platform malware like macro viruses that affect both *NIX and Win systems. Too many people don't want to spread infected files on their business network, customers or friends and family, so please stop talking for all of us.

No, we don't need it.

1) As macskeeball stated, there are no know viruses in the wild.

2) I don't care if I do pass on a Windows virus. If they get infected, it's their own damn fault for using a Windows PC.

I don't mean to sound heartless here, but I'm not about to start running virus software on my Mac just so I can help PCr's avoid viruses.

If and/or when a virus is made that'll affect OS X, I'll start using something like ClamXav.

Although there are no known viruses in the wild that directly effect OS X, if you exchange files with PCs much its absolutely possible you might receive a file that was infected with a WIndows virus, and if you then transfer that file to a Windows PC the virus will affect the PC and cause the generation of even more spam. Of course, this also applies if the Windows PC is Windows running on your Intel Mac.

So... if we don't have any viruses, how do we confirm that this software actually works? I mean, what exactly does it do and do we even need it?

do I need an antivirus on My Mac? Don't think so, but have clamxav.. for just in case :)

Slower than Molasses on a cold morning... but hey, it's free!