People over at Austen Blog have been raving over this adaptation of Elizabeth Gaskell's novel (online text) for a while, so I decided to look it up last night. Here is the BBC website. I don't think it has been ever shown on Masterpiece Theater, but it is available on DVD.
Daniela Denby-Ashe plays Margaret; Richard Armitage plays John Thorton (and the women over at Austen Blog paid a lot of attention to him, surprise surprise).
Richard Armitage (wiki)
The Gaskell Web