I found out why I couldn't figure out what you meant, Stefan. The file I needed to set the option in was "admin/setting.php". I was looking for "admin/settings.php". DOHHH!!!
I did what you instructed and it works like a charm. Thank you very much, sir.
Edit: I just noticed that on the first post if I check the "Send User to forums" checkbox (from Firefly's hack), it sends the user back to the forum display. If I check it on a double post (when Prevent Double Posting is enabled), it will not send the user back to the forum display. Instead it sends the user back to view the message. Is there a way to fix that so it will work with the Send User back to forum hack?