I think that Buffalo will be able to keep one of them. I know that of the two, it is an incredibly hard decision to make. For me though, Drury is the captain material, the guy who can make a team, while Briere is just a fancy skilled player on a team full of them.
In a clutch situation, I'd rather have Chris Drury on the ice then Daniel Briere, even though both are great players and both are top line material.
If Washington is finally in the mode to spend money, I would like to see Briere end up there. That would be fun to watch, especially with Semin showing his skill and a lot of the younger guys on that team being pretty good in the third line checking role.