The latest version of TrueCrypt, can create a protected pocket of your hard drive that’s virtually invisible to prying eyes. Encryption, once a relatively obscure mathematically, has become a crucial method of keeping data from falling into the wrong hands in the Internet age. It works by creating a virtual disk on your hard drive and all you need to do to ensure that a file or folder is encrypted to store it on the virtual drive. Version 6.0a even allows you to run a hidden operating system from the encrypted drive, or encrypt an entire system drive on Windows Vista and Windows Server 2008 systems (but not XP). And best of all, it is free open source software.