I have been asked several time recently whether free(as in beer) antivirus programs are ‘just as good’ as the paid “Name Brand” offerings.
The short answer is no. However if you are cash strapped then you really should install some sort of virus protection even if it’s free.
The problem with Free Antivirus:
They are deliberately restricted to a subset of features which are available in the “Pro” version and the vendor is hoping you will upgrade to a paid subscription. For example AVG Free Edition
They may be an open source offering that is being developed and all the cool features are a while down the development track. For example ClamWin.
The main thing missing with the Free Offerings is real-time threat detection. If you are a Windows user and you use Internet Explorer or any of the inumerable downloading programs such as Limewire. The threats aren’t coming in as attachments to emails. They are being delivered in real-time over web protocols. Free AntiVirus software doesn’t protect against this vector of attack. ClamWins own website has this admission “Please note that ClamWin Free Antivirus does not include an on-access real-time scanner. You need to manually scan a file in order to detect a virus or spyware.”
Another issue with the Free offerings is that the Virus Definitions which is what gives an Antivirus Program the ability to recognize a virus may be delayed by several days because the Free version is restricted to one download every X days. If a virus is propogating via email or network you want to get the antivirus definitions as soon as possible. Only a paid subscription service will gaurantee that as soon as the vendor has a patch your Antivirus client will be able to download it.
So in the end you need to make a decision as to whether you want to risk an infection which will only be picked up perhaps several days after it has occurred or pay your $80 to $100 per year for Antivirus that has real-time on access scanning of both files and network traffic.
So for the average computer user I would thoroughly recommend forking out the yearly offering of cash to the Antivirus Vendors.