Hi twinchoke:
You should be able to open any midi file on your pc. you can also use music software like cakewalk and cubase to open your files (midi files only). on cakewalk you can view notes from your songs file and edit them too.
Since you are using an XG file, i recomend that you download any yamaha xg plugin (you can find them at any yamaha website)
www.yamaha.com Samer Kadoura