"The Thing" (1951) - its fast paced dialogue (possibly the best in any sci-fi/monster flick), fine acting and awesome score (by Dmitri Tiomkin) absolutely rock! It always makes me shiver.
I love the 1951 version of "
The Thing from another world"
James Arness has such a presence the few times that he is on screen in that movie. I think that his not overdoing it and not appearing too much throughout the movie is what makes it such a thriller.
As you mentioned, the score rocks and it adds such great anticipation, the building up of fear, everytime The Thing is about to enter the scene.
I can remember being a kid and watching this movie for the first time, late at night with my father, and loving it.