I say you go with the 330xi. It's easier to install nicer seats in the 330 than squeezing more power out of a 325.
Do either (or both) have the cold weather package? You know, it comes with a nice little pass through bag just for skis... You may be the only person I've ever met that could/would actually use it... Mine just responds to pressure changes in the cabin (like, say, when i roll down the windows) by filling with air, busting out of it's case, and flailing about the backseat like a cross between one of those air-filled thingies at a used car dealership and a busted air cylinder.