CE-Infosys provides a free software for Windows PC that allows you to enhance the security of your desktop computer by setting up pre-boot passwords (pre-boot access control requires you to enter your UserID and password before the system will boot up), AES encryption for Hard disk, encryption for CD / DVD as well as other media such as ZIP drives, USB thumb drives or Memory sticks. One can even encrypt of Individual Files or data that are to be transmitted via Email or FTP.
There are two encryption methods available, one that will keep your data encrypted prior to boot, and one that will encrypt data on-the fly. If the data is encrypted before boot, your hard disk can only be accessed with the proper password (even removing the hard drive would still keep it protected).

Link- CE-Infosys