Personally, I don't use any. Why? because I find them unnecessary in the world of linux and on my box. The last real virus threat I remember was in january, dealing with the RST.b virus and that wasn't even that big of threat.So I need not worry. Although it would be a good idea to use some sort of virus scanner software if you're running some kinda network, with webservers, or running a site like, let's say, sourceforge. Where the viruses could spread more rapidly due the fact that they don't scan the binaries that they have for download, or so I've heard. I can see how that would benefit. But other than that, I don't use any virus scanner <img border="0" alt="[Blah]" title="" src="graemlins/blah.gif" />
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By the way, if you're just that paranoid, I found a decent article on anti-virus software for linux, here:
The Article