t's instant pain without the interest rate gain. But are debit cards really safe? First, a definition. You know how a credit card works. You use your credit card to pay for something. Then you get the bill in the mail, usually within 30 days. A debit card looks just like a credit card. Mine has the Visa logo on it. But when you use a debit card, the money is pulled directly out of your bank account. No bills later.

It's also different than your automated-teller machine card, in which you type in your personal security code before you can withdraw money or make a purchase. A debit card requires no such personal identification number; it works just like a credit card in which you simply sign the receipt.

Reporter Susan Okula recently posted a query in a newsgroup that asked people whether they've embraced debit cards as a means of paying their bills rather than using their credit cards.

Several people - including me - said they did use debit cards, chiefly because of the peace of mind they provide. Paying as you go is a great feeling. But Decision Center columnist and tax expert Jeff Schnepper took the opposing view. Schnepper says he uses a credit card for the "float," the opportunity to use someone else's money between the time he makes his purchase and the time he pays his bill.

Not long ago, I was firmly in Jeff's camp. I couldn't imagine why anyone would use a debit card and be forced to pay up immediately for something that can be paid for in perhaps five or six weeks. But within the past year or so, I've gradually moved into the debit card camp, more for psychological reasons than for financial ones. In a strict financial sense, I think Jeff's right. Using someone else's money for free is the best deal.

But like many financial choices we make, choosing to use a debit card has more to do with how we feel about our money - about being debt free, about paying as we go - than it does about economics. Credit cards, not debit cards, make economic sense.

For me though, moving to a debit card was part of a lifestyle change. In 1996, my family moved from New York City to the country - in our case, to New York's Hudson Valley. At the same time, we made an effort to streamline and simplify our lives: to spend less and to make our lives less complicated.

We used our debit card for big purchases, like furniture and rugs. When we later took a two-week vacation to Nova Scotia, we used our debit card so bills wouldn't spoil our vacation memories. When the holidays rolled around, I used my debit card - or checks - to purchase gifts.

But even those of us who love using our debit cards must face up to some big negatives about our new best friends: They present a big security issue and they do nothing to protect you if you buy a shoddy product or service.

As I mentioned earlier, you don't use an identification number with debit cards, so it's easier for thieves to make purchases either on the phone or the Internet. They simply read off or type in your account number and voila, they've just bought something with your money. And with debit cards, the money comes out of your account at the time of the purchase. Until you discover the error and prove you didn't make the purchase, that's money out of your pocket.

A stolen debit card could literally ruin your finances in the short-term, in which your monthly payments are returned because of insufficient funds.

Credit cards win on both those counts. "The law allows you to withhold payment on a credit card charge if there's a problem with the merchandise you buy," says credit expert Gerri Detweiler, author of The Ultimate Credit Handbook.

But that same law doesn't apply to debit cards. How could it? Once you've purchased something with a debit card, the money comes out of your account and the merchant has it. It's just like paying cash. "Short of hiring a lawyer or going to small claims court, you're stuck," Detweiler says.

The protection offered by credit card issuers can be valuable. American Express, for instance, takes a very active role in protecting cardholders. I can remember a couple of times when I received a bill for a product or service that I either had not received or that was faulty. I called American Express. They removed it from my bill immediately and investigated with the merchant. Credit card companies like American Express certainly have more leverage with merchants than I do. Likewise, my husband recently had some items on his American Express bill that he didn't recognize. He called American Express and learned that they were bills for pornographic material. American Express investigated and discovered that the orders had been placed from the phone of a local merchant.

My husband had bought something at that merchant, an employee had copied down his credit card number and used it to order the pornography from the phone at work! The charges were taken off my husband's bill and the merchant got into some trouble with American Express.

Now consider this: Last summer, I purchased some handmade toys for my children from a toymaker's shop in Digby, Nova Scotia. I used my debit card. I received the toys in the mail a couple of months later just as I ordered them and in perfect condition. But what if I hadn't? It would have been up to me to deal with it long distance. From now on, I will probably use my American Express card when I'm dealing with unknown merchants, particularly in other countries.

Perhaps the biggest negative, though, is the security issue. Under federal law, your liability on both credit cards and debit cards is limited to $50 if someone steals your card and uses it. That holds "as long as you notify the bank promptly," Detweiler says, which means within two business days. But there is a big difference between debit and credit cards here. If someone steals your debit card, the money may already have come out of your bank account by the time you notify the bank. Then you must try to get the bank to put it back in.

A couple of years ago, on a cold Saturday afternoon in January, my wallet was stolen a few blocks from my home in New York City. I realized it right away, walked home and called the bank that issued my credit card. The thief had already charged $2,500 worth of jewelry on the card. What if I hadn't noticed the missing card until Monday?

When I got the bill, the jewelry was listed. Of course, I didn't pay for it. And it was later taken off my bill. But I'm certainly glad it hadn't already come out of my account.

So, what's the answer? I'm not going to stop using my debit card. It's my new best friend. But I'm going to be a lot more careful with it. And I'm going to use a credit card when I don't have experience with the merchant.