CCs vary greatly, some your liable for the every purchase up to $50, and have to pay the first $50 of very purchase over that. Which can be a really big ouch is someone really maxes up your card. Look in your CC agreements and terms of service, it will explain what you have to pay if your card or # gets stolen.
Now giving your CC# to sites be very very careful, especially if you use IE. As there are 3 security holes that allow people to sniff and grab passwords and anything else you type in. It's not the site you are on, but it's someone listening to a port on your computer. IE someone is standing next to you and you rattle off your credit card into your cell phone. And that person writes it down. This is really how open IE is on that type of thing.
Do inform you company, have them issue you a competely different number and freeze the other number. Do know where you stand in a case of faud with them, if the person rings up a lot of little charages, you may have to pay for it all. As not only anything under $50 isn't checked, a lot of companies will not eat all that money. As the CC company still has to pay for all those items bought, they don't get out of it. So a lot of time they just send the bill to you.
But seriously if your going to charge online go with a CC company that gives you virual CC #s, they are a one time use, and no one can get you real credit card # even if then grab it from IE. Quite a few companies are doing it right now, the ones I know for certain as I have the cards are Citi and ATT.
Good luck and I hope you get the money back.
Kit