Folder action to change file extension and automatically opening it.

Sorry for such an basic question, I tried searching the forums but all topics that was about similar situations returned as a forum error, bad request.

So what I would want to do is:

  1. A PDF file is downloaded, but the extension is .asp
  2. A folder action changes the extension to .pdf
  3. Folder action opens the file with Preview

I am running Snow Leopard, if that makes a difference.

I would be very grateful for help with this, I realize that this is something very simple that I probably should have learned to do by myself.