“Listening to the sound of musical instruments is unlawful (haram), as the Messenger of Allah (Allah bless him & give him peace) said: “Listening to songs is a sin” (4/345).
http://qa.sunnipath.com/issue_view.asp?HD=1&ID=1786&CATE=142
(or search {music} in the “answers” search engine, it’s the first link)
footprints on the sands of time 
subhanAllah it takes away from so much as well…
The Prophet (saw) said: “In my ummah there will be people who allow musical instruments… Then during the night Allaah will destroy them by causing the mountain to fall upon them, while He changes others into apes and swine. They will remain in such a state until the Day of Resurrection.’”
-Bukhari