LockNote is a free, efficient utility, that encrypt your text file using a user input password and the military grade AES 256-bit encryption technology. You only need to drag and drop the text file into a LockNote window or on to the LockNote icon and they will be encrypted automatically.
This is a portable application (312Kb); you can carry it around on your USB stick. You can move LockNotes wherever you want, as often as you want. A LockNote document does not require much more hard drive space than an unencrypted document.
However, though LockNote is simple and powerful encryption utility, the main drawback is, it only supports text files. Download LockNote from here.