Microsoft Security Essentials
Released by Microsoft in late 2009, Microsoft Security Essentials sports more than a typically verbose Microsoft name: it's also a really good antivirus. Leightweight enough to run on older machines without cripplign their performace, yet competent enought to handle most viruses and malware out there.
AVG has become synonymous with free anti-virus, and there's a reason for this: AVG offers complete malware protection, with considerably less blat than the top pay-to-use antivirus clients. And while AVG Free does constantly remind you that you could pay for the professional version of the program, it does this withour ever getting in the way of the progrma's core purpose: protecting you from viruses.
In terms of simplicity, Avira's right up there with MSE. It's faily lightweight , too, so the comparison is quite apt. While Avira does have a paid profession version to peddle, much like AVG, it's not quite as aggressive as AVG in peddling it. Avira is sold and worth looking into for sure.
If this competition were for the collest name, the piratey Avast! wouldwin hands down. Even though that's not what we are discussing, Avast! stands up pretty well. This is one of the top free anti-viruses on the market, and for good reason: it's remarkabley complete. Expect great all-round protection, including against trojans and spyware. You can also expect constant reminders that there's a free version you can upgrade to, on your desktop and in your inbox. Still, the protection is solid.