Avast Antivirus

Avast! Free Antivirus finally debuts a version that is optimized for Windows 8. While the application doesn't function as a Modern UI app, it takes design cues from the operating system. There are plenty of updates that make avast! Free Antivirus one of the best free antivirus suites.
Features
avast! Free Antivirus is loaded with tons of features. From the home tab you can gain quick access to your system status, virus scan, software updater, stats, and the market. Features like the firewall and SafeZone require a premium subscription.

The software updater that's included with avast! Free Antivirus alerts users about outdated applications that are installed but only offers a link to the program page to download the latest update. Paying for a premium subscription will allow you to update your apps within the application. There's even an option to update automatically in the paid versions of avast!

avast! Free Antivirus offers more than just virus protection. The application also includes "cloud services," which gathers information from other avast! users to compare the reputation of similar files. These updates are constantly streamed to and from avast! so users don't have to worry about downloading updates.