Most of the replies are missing the point. You do not only want to protect the rest of your system from your browser. You also want to avoid your browser doing anything an attacker wants when he finds an exploit in it.
If you try to solve the problem with virtualization, different users or another solution like that, you would have to run multiple browsers for different sites to avoid browser exploits causing trouble. Of course, it is always better to run network applications as a different user than yourself, but browser exploits are somewhat hard to contain that way since the things attackers want may be in the browser itself (cookies or, hopefully not, saved passwords). I have to restate what I wrote in another thread: looking at the security record of the popular browsers it is scary we use them for online banking and other security-critical functions so carelessly in our everyday life. -- Jussi Peltola
