Protecting Non ASP files

Hi all

I have used UltraDev and ASP to protect access to my intranet
http://www.youngengineers.com.au/Intranet/Division.asp

The problem I have is that documents are not protected
http://www.youngengineers.com.au/Intranet/Documents/RolesRespYEANCMay04.doc

I need any advice on how I can set up a streaming script in ASP (or
similar) so that my documents (Im guessing) will have a protected url
eg.
http://www.youngengineers.com.au/Intranet/Documents.asp?docid=12344

I have no control over the ISP or any server side protection such at
htaccess or folder security, so using ASP and a database on the server
is the only option.

You time and advice is greatly appreciated.

Steve