PHP Code:
if ($_SESSION['customer_id']) {
  $show_blah = true;
} 
If you have the sidebox setup with a control for when to show it like the featured.php sidebox ... you can use that after the:
PHP Code:
// test if box should display
  $show_blah= true; 
Then, surround the remaing code with the IF:
PHP Code:
if ($show_blah == true) {
// all code here

}