January February July 2011, there are at least three four perfectly legitimate free antivirus products for Windows. In my order of preference they are:
- Microsoft Security Essentials
- Avast Free Antivirus
- AVG Free
- Avira Free (why?) (fallen from grace due to user pestering)
These are the ones I have used. There are at least 6 more to choose from.
Please note that the following products are NOT free to use:
If you’re using one of them and not paying for it (unless of course your organisation has paid for it), you are at risk, as malware authors use warez and similar types of “freebies” and “cracked versions” and “key generators” to infect your computer with the very software you’re trying to defend against.
The only (temporary) exception to this is time-limited versions of antivirus software you usually get with brand new computers, but you must do something about those as soon as the gratis period expires: either buy the product or uninstall it and install one of the free ones.
Remember, an expired antivirus that is not updating its definitions is almost useless.