Hi, I am probably piling on but TEX is a commonly supplied application with distros that is widely used in the publishing industry, though this won't likely help with M$ products but don't you intend to get away from XP?.
I found this site:
Free software for composers, by The Linux Information Project (LINFO)
with a quick Google search using "linux sheet music display use midi" keywords. You can probably do better by refining it. Note use your words linux, midi, music.
You might look into KDE, one of many window managers for Linux which greatly simplify through the use of icons, images, buttons and sliders. They seem to have a bend in the music area.
Hope you enjoy the new mobo, be sure you get the fastest cpu you can afford especially if you are doing commercial work.