The Dracula's Castle intro track from Castlevania: Symphony of the Night, right after the game came out in Japan. MP3 was strange and mysterious back then, and it was from an ancient and obscure website by a Japanese speaking gamer who was, AFAIK, one of the first to try and get widescale exposure to Japanese game OST albums on the net. He'd post selected tracks from OSTs with info on the composer, date published, proper name of the album, etc.
The Video Game Midi Archive was a hot thing at that time, so you can imagine the magical quality this one side had to it - very often it had the same tunes from the same games that you'd see sequenced or remixed on the VGMA, except in this new, stunning quality format.