Flash Drive Encryption/Password Protection

[BOB IROC]

Does anyone know of a FREE and easy to use program that can password protect the data on a flash drive?

My boss put me on a mission to find FREE software to do this. More and more teachers are beginning to use flash drives to store their data and I guess it was brought up in a meeting what are they to do if their flash drive is lost or stolen to keep their data safe. I have come across a few "shareware" titles but most of them are like $20 or so and my boss doesn't want to pay a penny. Since they data they are (or at least should be) storing on their flash drive should be primarily school/work related it is felt (by the teachers and administration stafff) it is technology's responsibility to make sure that data is safe. I guess the end user (in this case being teachers) do not want to assume any responsibility for their data.

So if anyone has come across and/or used such software I would just like it to be easy enough to use for the average computer user which doesn't know much. I came across this in my searches (http://www.penprotect.com/) but that states its $20 for a single license. This looks easy to use but is not free.

Edit: I also would like to find something that will run entirely from the flash drive and not require anything to be installed locally on any computer. A couple free ones I have come across require a software install on the computer and then an application to be run to encrypt the drive.