While I sequenced this, it was all done from W3sp's arrangement for piano. All credit really goes to him. It certainly differs from the original, but he's done a spectacular job. Again, this is just a MIDI of W3sp's rendition. Download his sheet music and hear his MP3 at:
http://www.gamemusicthemes.com
It's under the PC section.

A note on the composer... I've credited the primary composer per game credits: Michael Land. And as far I know he is the main composer for the game "The Secret of Monkey Island", however Barney Jones, Andy Newell and Patrick Mundy are credited as well, though regarded as secondary composers working at external companies.
(http://imuse.mixnmojo.com/history.shtml)

Yet more sources claim Chris Huelsbeck and Rudolf Stember took part. I certainly wouldn't be surprised if a composer like Huelsbeck had a hand in it. I don't know the details, but the information is provided just so you're informed.
(http://www.mirsoft.info/gmb/musician_info.php?id_ele=OTA=)
(http://www.mirsoft.info/gmb/musician_info.php?id_ele=NDY2)