If you want to protect certain sensitive data, the most viable and simple solution is data encryption. There are many encryption programs to choose from, but when it comes to ease of use and value few can compare to the open-source TrueCrypt software.
TrueCrypt can create a virtual encrypted disk within a file and mount it as a virtual disk that can be accessed via a drive letter. It can also encrypt entire hard drive or removable media, such as USB flash drives, floppy disks, and memory sticks.
Any file that is saved on the encrypted virtual drive is automatically encrypted on-the-fly, and can only be accessed while the drive is mounted with the correct password or key.
TrueCrypt supports 11 algorithms for encrypting your private data, including such algorithms as AES-256, Blowfish (448-bit key), CAST5, Serpent, Triple DES, and Twofish.
The best feature TrueCrypt provides for the user is the ability to create a hidden drives. It is the best way to prevent others from discovering that some data even exist.
The program has quite simple interface and the regular user can handle it easily. The useful tips in the comprehensive web help manual and volume-creation wizard provide excellent guidance.