Back in the day, the only intelligent way to pay for anything abroad was with traveler's checks -- that is, until ATMs became as common as Americans in jeans. Here are the pros and cons of three payment options abroad. Traveler's Checks: They're not convenient -- you need to exchange them at a bank during regular business hours, an American Express office, or at your hotel. (Airports have notoriously bad exchange rates and high fees.) Wherever you exchange them, either a flat fee for the service or a percentage ranging up to 10 percent is charged. But they are still the safest way to carry your money -- and still the preferred method in Third World sites where ATMs are not as prevalent as they are here. ATM Cards: There's an ATM on most street corners in Western Europe. Most will accept any ATM card that's part of the Cirrus or Plus network. The rate of exchange is favorable -- usually 1 to 2 percent better than what you get with traveler's checks or even cash. Most European ATMs only have numbers on their keypads so if your PIN includes letters, make sure to memorize the num-eric equivalents (and most will only accept four-digit PINs). Credit Cards: Credit cards offer favorable exchange rates -- but they usually tack on a "foreign exchange fee" of 1 to 2 percent. While virtually all stores and tourist establishments will accept credit cards, many will discount for cash. You can use a credit card to get cash through an ATM, but the interest rate usually hovers at around 20 percent and there may be additional fees.