Softpedia came up with a list of best free anti-virus software. Unfortunately, the list is missing the best of them all – AOL Active Virus Shield. AAVS is powered by Kaspersky Labs anti-virus engine, which is rated by many anti-virus reviews as the No.1 in Virus detection rate. AAVS gets updated daily and is prettly low on resources. Though the AOL logo on the software may put many people off, it is only a slightly stripped down version of Kaspersky’s commercial product. Interestingly, it also has a built in spyware check tool, so you reduce the burden on your system by cutting down one more daemon process.
I was using AVG previously. When I ran AAVS for the first time, it detected a few minor viruses which were missed by AVG free edition! If you are searching for a free AV tool with low footprint and CPU utilization, look no further. Here is the download link to AAVS.
My Two Cents 