A debit card makes it easier to manage your finances. However, you lose some legal protection there. In addition, there are stiff fees if you are not careful. Additional fees of $35 are common for over-limits and late payments. Be aware that a new law takes effect on July 1, 2010 that requires banks to ask your permission to put you in an overdraft plan.

If you have a credit card you can pay it off each month without interest charges.

Your protection is much better against theft with a credit card. You limit of liability is capped at $50. But with a debit card you will usually get a credit for the stolen amount.

If you dispute a charge, you will have better results with a credit card. 

Your credit score can be positively affected when you use a credit card. All payments there are reported to the credit card bureaus. Not so with a debit card.

The rewards given by banks for using credit card is better than you get with a debit card. You need to pay $4 to gain just one point on a debit card.

Overall, it is to your advantage to use a credit card for larger purchases and a debit card for smaller buys.