Laura,

well, technically it's not really about Arthur, but Nick Keir wrote a song called "Avalon", it's somewhere in the DT. And there's Jake Walton's "Tristan's Song", which also isn't actually about Arthur himself... There are probably many more songs, but these are the only two that I can think of right now...

T.

P.S. What "very good version of the book" have you read?