Actually you can "flash" a Vivitar 5340s and it becomes a DC-500 with all the same settings and options.
Instructions for "flashing the bios" for upgrades is in the DC-500 manual. If you have not done this for your DC-500, you should - definately improves operation, especially with a 1 GB card.
I bought a 5340s a little more than a year ago and set it up as a spare since both my wife each have a DC-500 - but have not seen any for sale in about a year.
I am getting ready to upgrade from my DC-500 and will be selling it shortly. However, I'm keeping the spare camera for her system. Make me an offer.