I've seen a reference recently (was it in a book review in last weekend's newspaper? -- I only ever buy a paper on Saturday) which suggested that the Armada theory was unlikely. Not that there are no Irish with Spanish ancestry, but that it's much more likely to be the result of Spanish/Irish trade than the Armada.

My wife has always claimed Armada-Spanish-Irish descent through her father, surnamed Dyas (ex Diaz?); when I pointed out the article to her, she merely shrugged.