Can I recommend Tom Erbe's comprehensive list of useful programs for mac users :

computer music programs . macintosh

at :

http://shoko.calarts.edu/~tre/CompMusMac/index.html

It contains the ftp address for the latest version of Csound for mac, as well
as many other intriguing mac music applications in both the real and non-real
time fields. Concise descriptions of each package are provided.

If you do download any music non-freeware (Tom's or otherwise), please pay for
it - the prices are very reasonable considering what you get, and the work
that goes into development.