I use Password Dragon written by Ramesh Natarajan. The publisher says the files are encrypted using BlowFishJ. It can be resident on a USB flash memory device. I have been using it for over a year with both XP and Vista, and have had no problems. their website is http://www.passworddragon.com/.
Note to FTC: I am in NO WAY compensated by the author or publisher!
BTW: The best part is that it is FREE! As in beer.