clamAv

Yes, it's quite good. But before installing any anti-virus software see the following:

Viruses, Trojans, Malware - and other aspects of Internet Security

Mac Virus Guide

I'm not familiar with this particular distribution, but it is included by Apple in all server versions of Mac OS X. It is also the AV scanning engine used in shareware applications Lion Cache Cleaner, ProtectMac and OTIC's ClamAV (currently out of date). You can also find it distributed with the freeware application ClamXav from either the AppStore or http://www.clamxav.com that has been widely recommended here by several Community users.

Full disclosure: I provide uncompensated tech support on the ClamXav Forum.

Booberoi wrote:

So what you are saying I already have it installed in Lion and dont need it?

Only if you have Lion Server. If you have the standard version it is not included.

That is up to you. People have very different opinions on whether or not a/v software is necessary for Mac. But, it can't hurt to intall it 🙂

Booberoi wrote:

I received anti virus software from CD Earth called clam AV

Just thought I would mention that the site is rated very poor by several WOT users. See http://www.mywot.com/en/scorecard/www.cdearth.com and comments. Google Safe Browsing does not show it as being a problems.