I'm not sure if jhc is still pokin around these parts - this was more than 3 years ago! There is a thread in here somewhere, probably the think tank, on how to determine the key of a song - most of the time.
I say its in the key of E.
The intro is just a 5-1-4 jam with the B, E, and A, all of which are majors.
The buildup is in B Mixo, further showing how it is in the Key of E because B-Mixo is the fifth mode of E-Ionian (did I say that correctly?)
Then it goes to the minor 2nd of E, the F#m, plus the chord buildup after that (E > F#m > A >B) is all in E.
I dont think this song could be in B, could it?