SSL encryption ensures that transaction information is sent securely but has a significant performance tradeoff in the browser environment. You may have noticed that our web site employs frames for easier navigation and more efficient page updates. With this in mind, we selectively place SSL encryption only on those forms and frames that need to be encrypted (i.e., when the credit card information is requested). Since things like our navigation buttons and menus do not need to be slowed down by SSL, we do not employ it there.
Unfortunately (but for obvious reasons) browsers won't show the safe "key" or "lock" unless each and every frame on the page is SSL encrypted. Thus, if only one frame is encrypted, the browser correctly reports that not everything you are looking at is "safe." However, the absence of the "lock" or "key" does not mean that the information you are looking at is not encrypted.
You can verify that a frame is SSL encrypted by right-clicking within the frame and looking at the frame info or properties (i.e., found in the "View" menu in Netscape and the "File" menu in Internet Explorer). Doing this when the credit card information is requested will indeed show that this information is being sent encrypted and any security concerns you may have should be relieved.