I've been playing with the latest Firefox 3.6 beta...and i have to say that I like it. One of the major differences between and competing browsers is that when you turn on In-Private browsing...it stays on even when you shutdown the browser and reboot the computer.
That being the case, your history, cookies, and online activities are always erased when you close the session. For hobbyists, this is a killer feature...plus the pages render beautifully.
Keep in mind, this is a beta, so if you are technically queasy about your computer, wait until the final release is ready.