Man... This song just makes me feel like growing a garden and joining Greenpeace! Seriously though, thanks to this song, this is probably the best credit roll in video game history! The song was composed by Rika Mrunaka(who also worked on other great titles like Castlevania: Symphony of the night) and performed by Aoife Ni Fhearraigh, an Irish singer.
Anyways, Metal Gear Solid is a game to be praised and remembered. If you missed its first incarnation, try at least to pick up it's remake; Metal Gear Solid: The Twin Snakes.