If you're already using Linux, you shouldn't still be thinking that only proprietary software (like F-Prot and AVG) can do the job for you. You should already be sold on the idea that open source software can be at least as good as proprietary software, if not much better.

That being the case, I wonder why you're recommending only proprietary antivirus software, rather than ClamAV. In fact, ClamAV, a fully open source antivirus software solution, is one of the best AV systems available in terms of its comprehensive protection from viruses.