If Pedro spends extended time on the DL and Pettitte comes back at full strength, you win this trade. Magglio is certainly an excellent player.
If either of those events don't happen, the other guy will profit more.
You probably need a crystal ball for this, or inside info from Pedro's doctors, but my instanct is to stay put. I'd take a gamble on Pedro, even more so since you need to make up ground. This is the type of deal that could bite you either way, but I think the odds are in your favor with Pedro.
Congratulations on the win - hopefully the first of many!