The only formal training I had was with piano between 4th and 5th grade, and sadly my live playing skills have probably decayed, but I can still read most sheet music. I just won't be able to play it as readily unless it is simple.
My first stab at computer music was with Impulse Tracker. Then I discovered Fruity Loops in high school, back then used a demo of FL 2.5 (an FL without Piano Roll? NO WAI!), and got hooked on that line of software up to today.
My other music-related endeavor goes into DJing, and music production has helped me in that area. Musical harmony and following keys is also important there, and makes the difference between a good and a great DJ set.