The Celtics will win in 7
The Lakers will lose in 6
Easy answer.
The Lakers will put a fight, but Dallas is winning either game 3 or 4. At home, and with their depth, they can abuse the Lakers. I'm saying Lakers win a couple of games, lose in game 6. Rick Carslile is a great coach.
The Celtics are winning both home games. I expect a break from the ref pressure, and Shaq is coming back, so Doc will finally stop messing with rotation.
But I wouldn't celebrate the Lakers defeat until they're done. Mavs, you can do it!