My personal, nonprofessional opinion about the most efficient antivirus:
1. User who understands what viruses are, how they spread, how to identify them, and how to not get them. (#1 leading cause of virus infections and all other computer security compromises for all operating systems is the user being dumb)
2. Don't use Windows (100% effective against viruses)
3. No antivirus. Just reinstall Windows from a Ghost image whenever you get a virus. (Dell consumer systems usually come with a way to do this for Windows and Ubuntu, depends on version and OS. I don't believe mini 9's will due to small capacity of SSD
, but you can still do it yourself. Not sure whether Mini 12 will or not. Can check on that for you if you'd like.)
4. No antivirus. Just reinstall Windows from scratch whenever you get a virus.
5. Commercial Antivirus Software (Useful in environments where the users are non-technical and don't require high performance or responsiveness, like businesses, gives end users and bosses the warm fuzzies)
6. Get a free program that doesn't offer real time protection or run in the background. Scan with it every couple weeks when you're not using the computer. Let it remove anything it wants to. Malwarebytes, Spybot, etc.
Vostro A90, 16GB SSD, 2GB DDR2, US-INTL Keyboard, FreeBSD 7.2-STABLE
Latitude E6400N, 2.4GHz, 4GB, 320GB, Opensolaris 2009.06 updated to build 118 Dell Tech Support agent