classic sci-fi help

[andy-m]

My girlfriend likes science fiction almost as much as me, but it turns out she's missed some important classic sci-fi films. ive spent the past few months getting hold of some and we've been watching them together.

theres 1 film I remember watching as a kid, but i cant remember what its called so i'm hoping someone on here can tell me what its called.

Its an old black n white film. Its set in america and theres a family living in a country house. over the hill an alien ship lands, and a boy see's it, but no one believes him. one by one, people go over the hill (Including his father i think) and when they come back, they seem a bit zombified and they all have the same X mark on the back of their neck.

It was a long time ago so i cant remember much more about the film other than it scared the bejesus outa me cuz i was quite young at the time.
anyone know what the film was called ?

[Anger]

Invaders from Mars

[andy-m]

thats the one !!

cheers