In comparison Truecrypt to Folder Castle is a great choice if you don't have a lot of computer knowledge. Truecrypt has it's advantages, the software is free. But is much more suited for the experienced user, it's a little harder to configure.
There is really only one thing I don't like about Folder Castle. Is I have to install Folder Castle on every computer that I am going to plug the USB flash Drive or external hard drive into. Truecrypt is stand alone on one of my external hard drives. I have a big hidden Truecrypt partition and a smaller partition that holds every flavor of Truecrypt, Mac Osx, Linux and Windows. I'm also able to use a stand alone .exe file from that partition. Then I can access my bigger Truecrypt partition, without installing Truecrypt on the computer I'm using.