Antivirus for Mac OS X 10.6 Snow Leopard

None.

But if you are required to have it or if you wish to protect Windows users from receiving viruses from files you forward to them, then an excellent free one is ClamXAV - CNet Downloads or MacUpdate.

Hi, and welcome to the forums.

There are no viruses that run on OSX. None. Zip. Zero.

If you're running Windoze on your Mac, that's the same as running it on a PC, so it needs all the same anti-everything stuff you'd use on a PC.

There is some "malware," such as Trojans, for Macs, though. But (unlike viruses that can get onto your system without your knowledge), you must approve their installation (via your Admin password) and/or operation (via the "This application was downloaded from the internet ..." prompt).

Appropriately enough, some of these Trojans are included in pirated versions of Apple software, such as iWork!

For the gory details, see Thomas Reed's [Mac Virus Guide|http://www.reedcorner.net/thomas/guides/macvirus].

Sophos is an excellent choice also. I do recommend turning the on access scanner off when
it is not neeeded.

Of course, if you are not sharing files at all with windows machines, an antivirus installation
on a Mac may very well border on being useless.