I bought this CD ONLY because I heard this thrilling soundtrack for a Ronaldinho soccer video that I had downloaded off the Internet, which some people thought was the Overture from Requiem for a Dream.
Unfortunately, as the Amazon website for this movie soundtrack CD does not have song samples from the CD, I had to actually BUY the CD to see if it contained that soundtrack. The closest track to the song that I was looking for was "Lux Aeternum". The rest of this CD, those tracks that did not repeat the main theme from the movie, I found pretty disappointing.
So I did a vigorous search through the Internet, and finally discovered that the track that I had heard was an orchestral remix of "Lux Aeternum", done especially for the first movie trailer for "The Two Towers". A Google search turned up a post on Aintitcool.com by someone with the screenname of Fatboy Roberts who described how two MP3 versions of this orchestral re-mix came into being.
As far as I can tell, this gorgeous bit of music does not exist in a commercially released form. It is certainly not one of the tracks on the "Requiem for a Dream: Remixed" CD. And so although I would actually like to BUY this music, I was able to find it only on Internet file sharing networks.
Use various combination of keywords such as "Lux Aeternum, "Requiem Overture", "Two Towers", "orchestral remix", "Fatboy Roberts" when searching for this piece.