Come across some excellent open source disk encryption software today.
•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 (pre-boot authentication).
•Encryption is automatic, real-time (on-the-fly) and transparent.
•Parallelization and pipelining allow data to be read and written as fast as if the drive was not encrypted.
•Encryption can be hardware-accelerated on modern processors.
•Provides plausible deniability, in case an adversary forces you to reveal the password:
Hidden volume (steganography) and hidden operating system.
Visit http://www.truecrypt.org/ to download!