Morientes is a 'proper' header of the ball - unlike Emile, who is just big. Emile is a pretty poor header of a ball - occasionally he'll get one on the meat of the forehead and it flew in, but his direction was nearly always pretty poor - for flick-ons and headers at goal. (Good defensively, mind, where you're not looking to aim it anywhere but AWAY!).
Morientes can hang in the air and get the power and accuracy. Just not sure how many crosses we'd get in, but having said that, Rafa likes two wingers, plus you've got Xabi and Stevie G crossing from deeper positions. Riise's crossing is erratic, but Finnan was always noted for his crossing at Fulham. With someone to cross to, there's more incentive for the team to get them in.