As far as I'm aware, the title originated like this: The original Quantum of Solace was a short story published in 1969 (?) where Bond finds himself talking to an ambassador at a dinner party. The'yre talking about relationships, and the way in which they break down eventually. Bond essentially says that no matter how badly the relationship ended, and despite the effect it may have had on you, if you can take away one worthwhile thing - be it a moment, a memory, or a feeling which was a good one - then you can move on emotionally and start afresh. The one good thing you manage to salvage from the wreckage is your quantum of solace - that thing which reassures you that everything you invested in the relationship wasn't squandered pointlessly. In terms of the film, that's what Bond is searching for. My take on it is that he completely invested himself emotionally in Vesper, only to realise he'd been betrayed and that it meant nothing at all. He's looking for something to salvage from it all, his Quantum of Solace, and since he can't bring himself to hate Vesper, it's revenge on the people who manipulated her into betraying him. He wants the satisfaction of knowing that someone payed for the cost it exacted from both of them.