That's quite a deal. Which side would you be getting?
For me, this trade doesn't look like a question of winning or losing, but of filling needs. If you need pitching, take the Pedro side. If you're already set on the mound even without Pedro, Berkman and Mags will give your hitting a huge boost. There's also a lot less risk to the Magglio/Berkman side.
I'd love to take a closer look at your roster and your league (scoring, how many teams) to try and figure this deal out - it's certainly a very interesting offer.