There are several ways to verify this:
Most browsers use a lock symbol
(Internet
Explorer and Firefox use lock symbols)
The address bar will show a HTTPS://
instead of HTTP://

In Addition:
All information concerning Passwords and
Credit card Numbers stored within the "my Accounts" section is
encrypted. No one, not even the USER can read this information
once entered. If a password is lost, the user must create a new
password. The credit card number is permanently encrypted as
well.
When purchasing, your credit card information
is transmitted to the authorizing credit authority using SSL
(Secure Socket Layer) technology and cannot be viewed in any
browser other that the one you are using.