remember that it's not which antiviruses have "gone further" that makes them find viruses, it's normally the detection rules.
e.g: some av's look for virus filenames, some look for harmful code in each file, some monitor certain parts of your system until it is changed, then see what changed it and if it's bad..
there are probably many other ways.
i would recommend the following things that haven't been mentioned:
spyware: spybot s&d
each of these scan mainly for adware/spyware, but spybot s&d has also found a few worms occasionally.
they are not online, but they are free