Sibelius

My 'New Media Intermediate Studio' studies include an introduction to Sibelius.

Avid Sibelius 7 claims to be the world’s best-selling music notation software meeting the demands of top composers, arrangers, and publishers, yet simple enough for beginners and students. The student version sets you back around AUD 289.00.

Sibelius is really easy to use, even if you haven't yet learnt how to write music, and it is lots of fun.
To see how it works, we searched for a free midi file on the web and dragged it into Sibelius. The notation, instruments and words all showed in Sibelius. It is then very easy to modify the score by dragging notes on the stave, swapping instruments, copying and repeating passages etc.