Firstly, Vancouver would not deal Cooke for that package. He's an impact player and serves an important role with the Canucks right now.
Secondly, I haven't seen any indication that Umberger has an attitude problem. He feels as though Burke has lowballed him, and given the fact that Burke's offered only $700,000 (or thereabouts), it does seem like he was lowballed. I'm not privvy to the negotiations but, not taking a team's offer does not mean a player's got attitude problems.
Umberger's set to become a UFA this summer. If the Habs want him, they can pursue him then. I'd like to see the Habs pick him up if he does become a UFA, because he's got some good skills, the size and maturity in his game to make an impact fairly soon.
As per the original post: no, I don't think I'd deal Langdon for Ruutu. Big fan of Ruutu's and have been for a few years now. He's worth more than Langdon, but there's just so few goons in the league right now that are as solid, cheap, and good for a team as Langdon is. With Montreal being a small team that can be pushed around, I think Langdon has an even greater importance here.
If Montreal picked up Ruutu, the team would be playing a chippier brand of hockey. Ruutu's often a player that will agitate and go after the opposition's better players, a la Tikkanen. How would the opposition react? They'd go after Montreal's top players. Without Langdon, we'd either see Montreal top forwards getting hurt, or having to defend themselves, or seeing Souray, Quintal and Komisarek spending a considerable amount of time in the penalty box. That ain't good for Komisarek's development, nor for Souray's wrist, nor for Montreal's defense.
Lastly, I don't think there's a chance in hell Vancouver would consider dealing Ruutu for Langdon. If they wanted to keep Langdon, they'd've done so back at the waiver draft and exposed Ruutu instead.