>>I found two copies of include_Security.asp, one in Dialogs and one in Dialogs/Tag. They're identical except for one line. What should I
change?

 

Both.

>>Is there a way to disable the Flash uploader and try the iframe uploader instead, or is that not a feature on the ASP Classic version?

 

Yes, you can use iframe mode by setting the uploader UploadType property to Iframe.