LindyK, z3ta+ is not the best GM Synth to use (tts-1 would be a better choice), but the answer for how to make MIDI select the correct patch is the same. Either import the MIDI file into Sonar or use virtual MIDI cables to connect Sibelius to Sonar (see
http://www.youtube.com/watch?v=57afXavIO7Q). Open the MIDI file with Sonar's Event List. Navigate to the beginning of the file (or prior to where you want the patch to begin), tap the keyboard Insert key. Right click on the event you inserted and choose Patch. Double-click on the data field in the 2nd column from the right to brign up the Bank/Patch Change window. Select the Bank Select Method (Normal), the bank (e.g., 0-bank 0), and the desired patch (e.g., virus bass 01). Now, when you play the file, the Patch message will change the synth to the patch you programmed. I hope this helps.