Since the web browser is the focus point for many attacks on your personal computer, why do we spend money and time on firewalls and security software that does not seem to catch things like fake antivirus programs?
I propose that you start using multiple web browsers, along with keeping up with security updates and updates for helper programs like Adobe Reader and Flash. Tune each browser for the different levels of security and privacy appropriate for your needs. You can have multiple browsers open, each pointing to different website and doing different things on the web.
You might want one running just for Facebook, and other social networking sites, to avoid Facebook tracking what you are doing with other sites that have a Facebook link, like button, or whatever Facebook comes up with to gather information.