TrueCrypt — Free Open-Source Disk Encryption Software
Homepage : http://www.truecrypt.org
Free open-source disk encryption software for Windows Vista/XP, Mac OS X, and Linux
* Creates a virtual encrypted disk within a file and mounts it as a real disk.
* Encrypts an entire partition or storage device such as USB flash drive or hard drive.
* Encrypts a partition or drive where Windows is installed
How to Video :
How to Create Encrypt Volume ;