Well, my experience is that no antivirus / adware / spyware / etc are safe.
Those are a tool to help you prevent from malicious threats but not means that they will protect 100%.
Some are a little better , some not but the result is the same, if you do not care about what you are downloading you will have probability to get infected.
So my personal opinion is watch every stuff that you download, do not download from sites that seems suspicious or that they are not serious companies because you can get infected somehow.
Most of people who makes viruses aim to Microsoft Internet Explorer so if you use mozilla firefox you will be safer, that not means that you will never get infected but it means that it is safe to use other browser as Opera or firefox instead of Internet Explorer. I use avast professional and the last version of Lavasoft ad aware 1.06R and I do not need more than that, even when I have plenty of antivirus software and spyware removers, etc I wish to have the time to test everything but I do not have time.