Know the reputation of the internet site you are buying from. Simply put, shop with companies you know. Their reputation precedes them. They are just as big and reputable as Waldenbooks or Borders. Be hesitant to purchase from an on-line shop whose name and reputation in not well know or researched.
Secure servers use standard encryption technology that is universal.
They are quite safe. Most sites will tell you if you are sending information over a secure server. You can check yourself by looking at the web site address before you submit your information. Most web browsers show a picture of a lock somewhere on their interface. Both Netscape and Microsoft comply with industry security standards.