Whether you just have important business files or are a paranoid psycho, TrueCrypt is free software that you can use to keep your files safe. TrueCrypt is free, open source disk encryption software for Windows.

You can use it to encrypt parts of your hard drive, flash drives, whole hard drives, and even your entire operating system. Encryption is done automatically, on the fly, and transparently so that you don’t have to worry about important data being stolen. TrueCrypt has a few different algorithms to choose from, and you can even combine them for ultimate encryption protection.

Use TrueCrypt if you just want to ensure your customer data is secure while you aren’t at the office, to keep the government from looking at those super secret world domination plans, or to keep the aliens from finding out where you live. It’s free and easy to use, and also available for Mac OSX and Linux.