Sibalius is a GREAT program, but very spendy. If you are just getting started, I would suggest Print Music, by Finale'. Last I looked this software was well under $100.00 dollars. There are also free notation, and sequencing (freeware, Shareware) programs avilible via the net, that you could get your feet wet with before making an investment. Furthermore, I believe Steinberg Cubase and Calkwalk have trail version on their sites you can download.
Paul Davis