Securing file access

["John M. L." <john () recaffeinated com>]

I have a project that involves a members only area on web page on IIS.
The members' only area is secured by a database (MS Access) so users are
authenticated by their name and some MD5 hash etc.  I need to allow files
(mostly PDFs) for download to authenticated users only.  In my opinion this
means that the files can not be stored in any www accessible folder
(regardless of any renaming convention etc, I absolutely cannot have someone
guess a file name to download).  In order to access the files, the database
would link a file to a unique id, so a page that validates the user would
then give access to the file stored outside of the www on the server.  Now,
this is where the real question lies.  How is this possible since the files
are not in a www accessible path, since a mere link to a file won't due.
Any thoughts would be welcome.  If I'm going about this completely wrong
that would be nice to no too :)  Forgive me if the answer is simple, I'm a
Linux fan and haven't used IIS etc for years.
One more note: IIS, MS Access and VBScript are not my technologies of
choice, but merely what I was given to work with.  I also have very limited
control over administering IIS.

John
www.recaffeinated.com