I'm a fan of the old horror films as well. But I remember when I went to the theatre in 1979 to see "Alien" when it first came out. My wife and her friend went to see a Disney movie - I had heard a lot about "Alien" before it first came out and I really wanted to see it. After the movie, my wife said that I was white as a sheet and shaking. I don't think that any movie before or since had scared me so much. Of course, that was a theatrical experience and, if I had seen that at home the way many of us see movies now, it wouldn't have scared me as much. That may be behind the physcology of seeing a movie in the theatre - it is so much impactive - re: "The Alamo."
A couple of observations on "Alien" - The score by Jerry Goldsmith added a lot to the atmosphere of the movie. However, for some reason, the director opted for a part of Howard Hanson's "Romantic" Symphony for the end title music which was completely at odds with what Goldsmith provided.
Cheers - Jay