A long and argumentative discussion on the Nottingham Trent University Bulletin Board, on the topic of "what are your favourite tracks of all time", spawned this compilation.
After a long (and very noisy) analysis of everything I've ever heard... ever, the final top 20 was compiled and put on CD. Problem is, with three tracks weighing in at the six minute mark, and one at seven, there was only room for the top 17 tracks. This is the third edition.
You can see the whole countdown, and sound samples, on the Top 20 section of the Book Of Heavy Metal.
It was never meant to be a series (as MS2 would have been tracks 18-34, and thus less quality) - but the name has recently been resurrected for a compilation of tracks that could be used as an education in metal for beginners, from the beginnings to the (almost) present day. Metal Storm II: An Introduction To Reality is that compilation.