Field level permissions in Drupal 7 What is the best way to create a piece of content with multiple fields... allowing users to edit the content as a whole yet blocking the ability to edit.

The setup I have is a piece of content that has 3 fields: Body, PDF, SWF... and a "Selector" (List Text) that's tied via dependancy. So the user chooses BODY, PDF or SWF and that's what available to edit and shown on the page when live.

What I want to do is add a PHP field... that's either:  


greyed out (unable to edit) if your not admin...  
doesn't show up in the Drop Down list... Can't select it if you can't see it
Shows up on the drop down, but the field doesn't show up in the editor without permissions.


I hope I'm making sense... I can provide an example if needed.
For Drupal 7, check out http://drupal.org/project/field_permissions.  


  The Field Permissions module is a drop-in replacement for the Content
  Permissions module shipped with CCK.


So for Drupal 6, use the Content Permissions module shipped with CCK