It all depends on film stock used. Aliens was made 5 years after An American Werewolf in London and is far more grainy and gritty. If you base the quality of HD releases on grain, you're going to be sorely disappointed with many old films. The higher the resolution and the clearer the picture, the more grain inherent in the film itself will be revealed. I guess if it bothers you, stick with the SD version of that film. I'll take the better colors and clarity.