Boys,
Ever mindful of the wear and tear on the psyche of the average Civ player, Lemon Labs has been working feverishly on this very issue.
(Actually, you gave ame a great idea.)
I have found a way to accommodate your musical request with some crafty XML editing. The file CIV4EraInfos.XML has the names of the background music selections in it. I have set them all to <NONE>, thus removing the BG music, but leaving the diplo and movie music intact. Simply unzip this file:
View attachment 261711
Into your favorite mod's Assets\XML\Gameinfo folder, or into Custom Assets\XML\GameInfo, and enjoy!
Tres simple!
Is there anything you can't do?