If you’re worried about security while you’re browsing the web (and you probably should), here is a simple solution that might actually work (or at least raises the bar quite a bit): BitBox (German)
In a nutshell, it’s a secured Linux system running Firefox 4 inside of VirtualBox. The browser can only access the resources of the virtual PC.
So to infect your real system, the hacker must: Break Firefox on Linux (which is hard), break Linux (hard), break through the virtual PC layer (not that easy either) to be able to infect your real PC (as opposed to just infect your PC).