In reply to goatee:
I really like the Ariege and that neck of the woods. It'd seem a shame to bypass it if you're 'doing' the Pyrenees east-west in chunks, even if there's more impressive stuff a little further west (in my opinion).
Some ideas in this destination article:
http://www.ukhillwalking.com/articles/page.php?id=3566
Peak wise, Puig Carlit and the Dent D'Orlu are two of the highlights of the area