cookies and HTTP authentication are not really very secure either of them...
you can always hack around their code... and it's sniffable. 

HTTPS is much better...

To elaborate more, cookies are not any form of authentication, inherently, because they're just client stored variables.  Anyone can have them, edit them and change them. 
You could encode some sort of key and try try to keep track of the users' sessions or just the users themselves. 
You are still going to have to do some sort of login technique.  If I'm not mistaken, HTTP authentication sets cookies anyway. 

If you're worried about "security" you'll need to subdivide "security" by what you're worried about.  If you need to be sure that a user says he's who he is, you'll need to use some sort of cryptography and authentication technique. 
If you're going to have content that 3rd parties cannot see, you'll have to invest some time and/or money or both into HTTPS.  If you're worried about someone rooting your box, you'll have to be very careful with your scripts, global variables, and even your webserver setup and version. 

When putting a smiley right before a closing parenthesis, do you:

Use two parentheses: (Like this: :) )
Use one parenthesis: (Like this: :)
Reverse direction of the smiley: (Like this: (: )
Use angle/square brackets instead of parentheses
Use C-style commenting to set the smiley off from the closing parenthesis
Make the smiley a dunce: (:>
I disapprove of emoticons
Other