XE.com is an excellent company to use when you are checking International Exchange Rates. It will give you up to date Exchange Rates 24/7 and conversions.
Onanda.com is another excellent company you can use to cross check International Exchange Rates. By using this company it will give you a great reference whether you are getting foreign monies prior to your trip or wanting to see what the International Exchange Rate will be in the country or countries you are visiting.
There are two major reasons why you should use American Express. First they are accepted in most countries all over the World. Second, you can usually find an American Express Money Exchange Center in most airports, hotels, malls or designated offices in the cities around the world. This is a good place to exchange your countries currency into the currency of the country you are visiting. Plus, if you haven't already you should also have an American Express Credit Card to take with you.