You can delete the history and cookies in any browser very easily.
The mode where firefox won't permanently save temporary files is actually a security feature. What most people don't realize is that those "encrypted" web forms leave completely unencrypted information on your hard drive. All an attacker has to do is inject malicious code to steal all of that information that is just lying around unencrypted. Think about that the next time you buy online...
In another example: someone can go to college to party and have sex, so lets all not go to college, because it's an evil place...
Natura naturata -- Spinoza
"Sapere Aude" - Dare to Know
"Extrico subjectio quod verum ero evidens" - untangle the subject and the truth will be evident