That is amazing how far you were able to trace your family. We have mine only up to the mid-1700s...Alexander MacArthur from Isle of Skye, Scotland. I'd like to know more, but have been unable to find much information.
I've seen a post on X-Marks where someone (don't remember the name, unfortunately!) has a Clan Arthur Clan Crest (MacArthurs and McArthurs, as well as many variations!) as their avatar...maybe we are related?!