I've just sent my track in! I know I'm going to lose due to the lack of originality in just re-orchestrating the theme, but it was very fun to make! :3
Keep 'em coming! It's great listening to all the contributions
If you need any more inspiration, I have just uploaded another version of the theme: "ScapeSorrow". It shows how a theme treated in different ways can produce a completely different piece of music:
http://soundcloud.com/runescapesoundtrack/scapesorrow