I'm more asking on behalf of others here, but it would be great if GOG could offer the original CD music as an alternative to the remixed version that GOG includes.
It isn't a huge issue for me as I have the original D2 CD, altough it isn't convenient to use as the nicely pre-packeged image file that GOG have cooked up for us.
It's debateable whether the remixed music is better or not (haven't spent much time listening to it tbh) but it sounds... strange to someone who has spent hours playing D2 in previous years.

Agreed. The orginal music was a very big part of the experience for me, and as all of my original discs are nowhere to be found, I wouldn't be likely to buy this unless the music was provided.
*edit*
So I couldn't resist and got the package anyway, knowing I could probably dig up the tracks on the internet somewhere. But to my surprise, the music playing was the orignial tracks! I have only briefly played into level two, so I couldn't say if there are remixed tracks after you get past the originals, but the good stuff was not omitted. Kudos.

You recognize them because they are remixes of the originals.
If you look at the DESCENT_II.inst with a text editor (it is actually a cue file), you can see the track list of the music that is included. If you want to listen to the music outside of D2, rename DESCENT_II.inst to DESCENT_II.cue, and load it into a CD burning program of your choice.
You will notice that every track is much longer than on the original CD, but there are fewer of them (8 in total from memory, as opposed to 12 from the original release).
Have a look here: http://www.descent2.com/goodies/music/d2_tracklist.shtml
This has the track lists of the various releases of Descent 2. The music GOG has provided for us is from "Descent 2 Full Version - New Infinite Abyss and Definitive Collection Release "