Dear Iarw, Do you happen to have permission from the group above to use their work as a basis for your own? This is a somewhat complicated question as far as possible copyright violation is concerned since much will depend upon a) how much, if any, of their piece The Downward Spiral did you use? b) have they released this work under a Creative Commons license (it does not appear to be the case), etc.? Welcome to the joys of IP law. Carolus (IMSLP Copyright Admin) 05:00, 2 January 2012 (UTC)
It is a tricky question.
The piece uses was done as part of the official NIN Remix project (remix.nin.com) which shares the recordings of remixes for free by permission of NIN and their record company. The score was a bi-product of that, which if shared under Creative Commons in the same way as the remixes, would it would appear would not be inv copyright violation (especially since all I used was a modified version of The Downward Spiral theme). I looked into the issue on the NIN forum (see http://forum.nin.com/bb/read.php?40,1209063 ) and the administrator there seemed to think posting up the score and parts for free would be OK.