After seeing the trailer to Alien Trespass, it definitely is that movie. I will see if I can get my hands on it, though I am not really a fan of sci-fi movies of the 50s, except War of the Worlds (better than the current version) and some other flick I don't remember anything about.
Thanks for the heads up, didn't think I would get that much information.
Other classic 50's films worth checking out: FORBIDDEN PLANET, THE DAY THE EARTH STOOD STILL, INVASION OF THE BODY SNATCHERS, and THE INCREDIBLE SHRINKING MAN.
Along with WAR OF THE WORLDS, those are the best of the era.