"Privacy" is the word that's on the lips of anyone even remotely connected to the Web 2.0 nowadays. But I don't care much about that. What you do on Facebook, Twitter, Flickr, or whatever, is your own business--and, worse, there aren't really third-party applications that you can download and use to self-assess your potential privacy pitfalls. You're on your own there.
However, when it comes to Windows--oh, yes, there's much we can talk about when it comes to the Windows operating system. There are always newer and stronger ways to protect your PC from intrusion, from third-party access via an unscrupulous exploit or unintended network connection to the raw, physical tricks one can use to gain access to your protected information. Makes my skin crawl just thinking about it, it does.
So, without further ado, let's take a little joyride through some unique free and open-source applications that you can use to lock down your PC without removing all traces of usability from your operating system. For just about the only thing worse than a computer nobody else can get into is a computer that you, yourself, have to jump through 30 hoops just to get into. These apps aren't going to be that, you have my word.