All...
I have uninistalled the works and installed OF 3.6.4 along with MySQL 5.1, and Red5 Plugin 1.11 (somewhat crazy to find but found it).
Even though the documentation for MySQL database install (for Windows) was no help I did find a good forum thread (below) which thankfully someone gave proper instructions (thanks Mike P).
http://www.igniterealtime.org/community/message/169495#169495
So once installing a fresh copy of Openfire, MySQL 5.1 and adding other plugins, I then attempted to install Red5 Plugin using the upload option under the plugins listing.
Once that was done, I restarted the Openfire Services (another point hidden obscurely in some instructions - Openfire using Win2003 should only be run via services, or something like that, rather the Openfire popup to start the application). For good measure I rebooted the server completely and waited for a while before testing the Red5 testpage.
I'm happy to say all is functioning well now and Spark is able to connect and no longer do I get 404 errors.
Thanks to all that helped.
Cheers
Tropolite