In my mac there also is an option for "private browsing" in Safari that doesn't save anything

I too use the private browsing but it is most important to click on Reset Safari - it will clear history, empty cash, clear downloads, remove all cookies, close all open windows and more.  I use it every time after I am through surfing.

Free upgrade to IE 8 has the option of "In Private" brousing which does not store cookies, history, etc.  If you click off by accident, you must re-enter all information.  The best part is it leaves you non-hobby history intact.  
I bought the wife her own computer a couple of years ago.  She rarely needs to use mine now, but would not matter if she did.  
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I use Opera that is installed to an encrypted removable thumb-drive so I don't leave any traces on the hobby laptop.

At least once a week I run DoD Wipe to clear out any traces of deleted files that are left on the drive.  

I also use CyberAngel on the laptop which is a security tool I use on all my laptops.  it is good for recovering a stolen laptop but it can also be set so that during boot up if you enter the wrong password it encrypts the hard drive or the portion that has been set such as where I store email files.  

The laptop I use for the hobby is not used for work and no one else has access to it.