No one single AV will be able to catch all viruses (especially 0 day nasties!) but I think that as long as people are security minded they will update their signatures regularly or allow the program to update itself. Companies are always on the look out for something new that hasn't been discovered yet and they are doing their best to patch their software in a timely manner. Good surfing habits and keeping in the forefront the ideas that AV software is only as good as the latest and most up to date files should protect the majority of us from getting to infected.