This patch introduces many new musical tracks that came in later expansions. Generally I used the Cataclysm expansion as a guide for rescoring the old zones, but of course many of the old zones are much different in their Cataclysm incarnation so my patch doesn't follow Cataclysm exactly. In addition to general new zone music, lots of sub-zone areas and interiors (i.e. caves, inns, etc.) have been diversified musically.
Download both part 1 (for your client of choice) and part 2 and place patch MPQ files in your game folder's "Data" directory. Part 2 contains the music files and is common for all three clients. See info.txt file included with the download for more details.