Avast works great when running through unsecured sites or when downloading p2p usaully when running limewire, but it literally catches anything and you should be running that 24/7, but for more protection use spybot at least once a week and run a check up on it, it really does take out some unwanted stuff, also if dont have already, ccleaner, it deletes all unwanted internet registry, cookies, and cache, to free up some virtually memory.