I can't say too much without knowing your WR situation. Do you really need Burleson? If not, keep MaGahee in case something happens to Henry. I still think Henry will get the vast bulk of carries, but I don't know how the Bills plan to work MaGahee in. Better to be safe than sorry in this case. I wish I had been able to pick him up myself, but someone drafted him way earlier than I would have used a pick to handcuff him.
Now, if you have a very thin WR corp where your stud is Keyshawn or something, then you may want to drop something to pick up Burleson.
What's your squad like?