I teach middle school and use Music Ace primarily in 6th Grade to teach fundamentals using a fun, video game-like presentation. In 7th Grade, I primarily use Finale Print Music to apply musical concepts learned in 6th grade: Music notation, arranging and simple composition.
8th Grade is time to apply all the above and to learn overall form and composition. Here I've decided on loop-based music software. I use Sony Acid Music Studio for it's ease of use and price, though Pro Tools or Garageband for MAC would do as well. Students do a series of composition projects based on different song forms (ie..ABAB) and they seem to appreciate that they are 'composing' royalty free music that sounds studio-produced.
That's my curriculum in a nutshell. All Music Tech all the time (except when I'm conducting Band). Classroom consists of 22 HP computers with 17 inch flat screen monitors connected to Yamaha PSR series keyboards.