Click on the link above or at the bottom of my post.
It's a really fantastic site (I think it's Russian) where you can download the ENTIRE soundtrack FREE. Once again, I think it's only possible because it's not an American site. Once you get to the webpage, right click on the little disk image to the right of each track, and click "Save Target As".
Then you're done. You've got whichever track (or all the tracks) of the "Children of Dune" score that you could ever want, free of charge. Just don't go and make tons of copies and distribute them, 'kay?
How did I find this gem of a site? By going to altavista, using their "Audio" search specifier, and oh so "brilliantly" typing in "Children of Dune". It wasn't that hard at all. In fact, it was sweet!