Lightweight portable encryption

[Michael Russell <mr_b15h0p () hotmail com>]

Hi all,
I'm looking for opinions on a light-weight, portable encryption program. 
 What I mean by that is something that has the following characteristics:
* The program should be small enough to fit on (and run off of) a USB 
flash-drive.
* I want to be able to encrypt 1 or more files with a reasonably strong 
algorithm.
* I should be able to take the encrypted files/volume to another 
computer and open the files with only the program and passphrase (ie, 
the volume isn't limited to use on the system that it was created on).
* Needs to be able to work at least on Windows 2000/XP (OS X/Linux would 
be nice as well, but not really necessary for me at this point).

I carry my USB flash-drive with me quite often, and am terribly 
concerned about leaving it in a computer somewhere or having it stolen. 
 While I don't keep top-secret documents on it, I do often have client 
files that, while not damaging, could be embarrassing to lose.

I've started using TrueCrypt (www.truecrypt.org), and it seems to work 
well.  I can run it from my flash drive, copy the encrypted volumes 
between computers, etc.  However, I would appreciate opinions from other 
people - opinions on TrueCrypt, or other programs with similar features 
that they have had good/bad experiences with.

Many thanks,
Michael