I have no problems rooting for Nash in the West, while a Celtics fan I was too young to witness the rivalry in the 80's, and the current rivalry isn't near as strong. Besides, I don't despise Kobe and his crew like I do Wade and his, I actually have respect for Kobe's game and find Gasol quite likeable.
Now that they've got Nash (one of my favorite players, and has been for quite some time), I'll be rooting for the Lakers as long as they aren't playing the Celtics.