Well I can tell you one thing, when you give out credit card infomation on the internet you have to be VERY careful because sometimes the page ins't encrypted. And if the page isn't encrypted, chances are someone can easilly find out the information. To find out if the page is encrypted, look in the address bar and make sure it is says "https". If it says that, then you are safe. If it doesn't, you are talking a BIG risk. If you want to know what kind of encryption is being used(64,128 bit) etc... just go on the page and do this:
"Right click" and select "View page info". The go to "Security and it says right there. That is if you are using Firefox. If you are using Internet Explorer, do "Right click" and select "Properties" and it says right there on "Connection". I hope this helps.