What I do is to use a single card for all my online transactions, and keep a fairly low credit limit on it so that even if there is a breach, my potential losses are limited. The most important thing is to have a unique and strong password for each meaningful site one uses, so that a single security breach does not lead to a complete identity loss. By meaningful sites I mean sites which have any of your personal details, financial details or the email account which you use for password recovery.

I don't worry about it much.  I hope that if a problem comes and I have kept my pin code secret, then the credit card company should not penalise me for anything that people have stolen.  So far I've been lucky.  Does anybody have any personal stories of where they have suffered personal loss because of this?

M. Malsikof – I agree with you, I used the words “rather biased” just because it's somehow out of topic, as I think Cláudia's question is not related to the security of our personal computers. So, back on track: :) When buying stuff online, I definitely prefer using services like PayPal, rather than giving my credit card numbers to multiple sites, since I estimate the risk of their servers being hacked as much lower compared to those of the countless web sites, with whose security policies I'm not aware at all.

No reason to be unnecessarily frightened.   Cancel the card and you can be issued a new card.

   Just to be sure, you might wait one month or so to be sure that you have a card  that is safely encrypted.  I would do that.

I, personally, am scared a bit. Actually, I agree with David and M. Malsikof that in this particular case (credit/debit cards) there is preventive measures that we can take, in order to feel more secure. Nevertheless, I'm not certain that our society is prepared to deal with many challenges, brought to us by internet changes recently. Moreover, all public visions and ideas I've read, seems to me quite vague. As an example, what about the personal information that will remain on the data storage servers for at least decades?

btw. @M. Malsikof .. your recommendations for Linux sounds rather biased :D