I don't use any. Only a basic free firewall from Zone Labs.
If something fishy is going on,I scan with Hijack This,and remove whatever is not supposed to be present. But,there never is,and will never be. Cause I don't push links I do not know what is in messenger or any other IM. I do not open or click links in mail from people I do not know who is. I do not visit fishy websites and click "yes,scan my pc now". Or install anything that just pops up telling you to install so that you can win a million dollars. Btw. I use FireFox,much safer than Explorer. In addition,I clean my computer regularly with CCleaner,something everyone should do