Its the one that starts around 20:20 in this WoW video. Most of the songs are Prodigy I think, but this one doesn't have any lyrics so I can't search for it. The movie is wow and its pretty boring so just let it play in the background or just skip to the end.
http://video.google.com/videoplay?docid=7458282830125289468&q=exploration+uncut&hl=en
http://video.google.com/videoplay?docid=7458282830125289468&q=exploration+uncut&hl=en