I've been using Myriad Melody Assistant for 9 years. Now it is 64-bit on Windows 7. I don't want to discuss the many advanced features but underline the ease of use for beginners and non-professionals. At the beginning, I used it for creating simple choir voice partitions/mp3s with the Virtual singer
voices. Thereafter, I started studying musical theory and composition. I use it for my exercises with the (piano staves). I have tried other software like Sybellius and find Melody Assistant the most user friendly and intuitive. I must admit, sometimes there has been some little bugs, but it has improved since. I know I could one day use it for composing larger orchestral pieces, but I am not there yet! So I can only recommend it to the beginners. For professionals, refer to other reviewers.