Eheh.. sadly I only know this song from the VGCats comic and didn't recognise the title at first...
Anyway it's a pretty good start, and recreating songs is a great way to get good at MIDI. But is there any way you can shorten your melody notes by just a hair? When two notes of the same tone play in a row, they actually overlap - one starts at the same time another finishes - so on many systems the second note isn't heard.