Recently the topic of Linux vs. Windows security has been making the rounds on the Internet. Specifically some well known technocrats of the Internet world have commented on the increased usage of Linux and how this will affect the overall usage of it as a vehicle for virus reproduction. This article from Security Focus does a good job of covering some of the basics of the discussion.
You will find the most of the time a self indulged guru will start saying things like “When Linux becomes as popular as Windows it will have just as many virus as Windows does now.” This logic is absolutely ridiculous and shows a distinct lack of understanding about the fundamental nature of computer security. If that were true then the mostly commonly exploited web server would be Apache (considering that it is responsible for hosting more websites than all other web servers combined.) but anyone who follows web attacks will quickly point out that IIS is the most commonly exploited web server. No, Microsoft Windows OSes suffer from a completely different problem. Bad design…
Lets be frank for just a minute. Microsoft Windows OSes are badly designed from a network security standpoint. Period! MS-Dos and Windows NT 3.51 (the OSes from which all subsequent Microsoft operating systems are based on) where never designed for global network connectivity. In the Blaster virus advisory, Microsoft went so far as to say the Windows XP was not designed to be run in its default configuration from within a hostel environment; like the Internet. Dos had no facilities for network connectivity until long after it was widely used. NT was designed to communicate with other computers but was designed to be used in a stand-alone, trusted, business network. This mindset is still prevalent in the Microsoft world and is evident from some of the mind-numbing default settings the Windows uses (default users having administrator access, non-privileged users being able to modify system libraries, firewalls the leave RPC ports open even when told to close them, etc..)
All of that aside there is anti-virus software for Linux. If you do a Google search you are unlikely to find what you are looking for since the vast majority of Linux anti-virus software simply gets rid of virus on their way to a Windows box (Linux proxy servers and the like.) The one Linux anti-virus program actually meant to be used to stop Linux virus is F-Prot for Linux. You can find a KDE based fronted for it here. If you really want to improve your Linux security you are better-off getting an IDS like Tripwire.
Unix (the grandfather of modern-day Linux, BSD, and OSX) has been designed, perfected, and used on hostel networks for 30 years now. If Microsoft actually developed their software in a secure fashion then the proportional number of virus would be closer to the numbers seen in every other OS in existence; not the other way around. If you want to see something funny be sure to check out this page from the F-Prot website. Its the current list of *nix OS virus that currently exist. Scalper is a FreeBSD worm, Slapper is a Linux worm (technically not a virus but close enough.) Two, thats it!