Conditional fields in views drupal 6
Views Conditional is a simple module that allows you to define conditionals (if xxx then yyy)
with fields in views. 


  Conditions include:
  
  
  Equal To
  Not Equal To
  Greater Than
  Less Than
  Empty
  Not Empty
  


For D6

Views - Control field display


  It provides a views filter that allows users to control which fields
  are displayed.
  
  To use, install the module, then add the Global: Control field
  visibility filter to your view. Select which fields are controllable
  (either defaulting to visible or invisible). This will add an exposed
  element that allows users to toggle the fields you specify on or off.