A friend once told me that if I 'clear my history' every time I'm on the net, the spammers will have a harder time finding me. Is that true?

No. By the time it's in your history it's already too late. Browser history is a file that just lists all of the sites you have been to. Clearing it every time might protect you from your wife though, should you have one.

Thanks for clearing that up!

How often should clearing the History or deleting the cookies be done? Is it a little paranoid to worry about speed, when you eliminate these "trails" that supposedly gets results quicker,and more customized to your interests? I only allow cookies from sites that I go to.