I see Fred, as per usual, is extremely helpful.
I came back to this thread to say that I might have given the impression that TrueCrypt was "complicated". It is not. I downloaded the Linux version (http://www.truecrypt.org/downloads.php
) and found it very easy to use - the program walks you through each step, simply and easily.
In my line of work there are plenty of documents that I handle that cannot be seen outside of my workgroup, so I took an ordinary 4GB flash drive, created a separate 1GB partition within it, and made that partition a TrueCrypt volume. The remaining 3GBs contains plausible but worthless data. The great thing is, the separate partition and the data within is by all accounts invisible. Even when this 3GB partition is empty and the TrueCrypt volume is full, Properties shows an empty flash drive with nothing in it. Even when I open the flash drive in gparted, only then do I see two partitions, but the TrueCrypt volume still appears to be empty. And I'm just using the basic version - the improved version of TrueCrypt goes even farther.
So yes, TrueCrypt is the way to go.