Thanks, Mike.
I also came across this service for realtime currency conversion:
http://www.yourcurrencyconverter.com
Perhaps I'm making this more difficult than it has to be (I always do that!

). It seemed like it might be "shopper friendly" to have them pay in their local currency rather than have conversion done by their Credit Card Company. If I can somehow get the converted value into the cart when they select their currency, that would be ideal.
Or does Paypal bill the shopper in their local currency when they actually check out? If that's the case, then displaying the estimated conversion may be enough.
-RayC