are you talking about Linux or Windows? all of these anti virus are for windows as far as i think. I used FC6 and now using Kubuntu 7.04. i don't have any problem. everything is fine without any antivirus.
There is no real need for anti-virus under Linux if and only if you remember the cardinal rule don't run applications as root ! Then there is little or no chance of any bug getting in your system!
But if you need an anti-virus use avira it's free, and in the latest anti-virus tests it rated higher then all the anti-viruses listed above
Added after 10 minutes:
here's a quick link
<url>http://avira-antivir-linux-workstation.avira-gmbh.qarchive.org/</url>
Most distros include a free anti-vir in the install CD/DVD so check if you have one