The following software and hardware lists identify the types of equipment you'll need if you intend to create MIDI scores for your product. You'll need fewer software and hardware components to prepare MIDI than you'd need to prepare digital audio. MIDI sequencers, keyboards, composition programs, and other MIDI equipment abound in the market. In addition, MIDI files are extremely efficient in terms of disk space usage. You don't have the massive additional disk storage requirements with MIDI that you have with digital audio.
You should, however, consider hiring a knowledgeable musician before you invest—he or she may have a suitable system already. That way you not only gain the benefit of experience, you also might save money on equipment.
Even if you are purchasing complete MIDI files from a supplier, you should test your application including MIDI playback on a Multimedia PC.