I'd advise you to get your card replaced right away, to avoid any more fraudulent charges getting posted to it. Call the number on the back of the card.
When I reported the fraudulent charge to my bank, they closed down the number right away so that the card couldn't be used again, and they said they'd send me a new card. I would have had to pay a $16 fee to get the new card rush delivered, but I didn't want to pay that, so I'm still waiting to get it.
Re: card fraud
See this page for info:
http://www.ftc.gov/bcp/edu/pubs/consumer/credit/cre04.shtm
When I reported the fraudulent charge to my bank, they closed down the number right away so that the card couldn't be used again, and they said they'd send me a new card. I would have had to pay a $16 fee to get the new card rush delivered, but I didn't want to pay that, so I'm still waiting to get it.
You may also be interested in these pages, depending on what kind of card you have:
http://www.mastercard.com/us/personal/en/cardholderservices/zeroliability.html
http://usa.visa.com/personal/security/visa_security_program/zero_liability.html