After finding out how to change the music of WoW, I still needed to find what song I actually wanted to have on my World of Warcraft login screen. I tried various songs I had on CD, but found that modern rock or pop music doesn't really go well with the WoW fantasy theme. Then I had the idea to use one of WoW's own song from another location. Now I could have unpacked the MPQ files to find WoW's music, but that being a bit unwieldy I was happy to find somebody else had already done that: MusicofWoW has all the songs of World of Warcraft, plus soundbites from some NPC's like Moroes. Now normally I wouldn't link to a site with pirated music, but since most of us already have the same music files on our hard disc, I think it is hard to argue that making this music available over the internet harms anyone.
By the way, I choose the Karazhan opera music, the one you hear in the ballroom, for my login screen, because it is such a catchy tune.