Alien 5 & 6: In a recent interview with Zap2It, Sigorney Weaver spoke of some of the details she interested in regarding the proposed Alien films:
"I'm not interested in returning back to Earth," yet sources say that much of the fifth film takes place when Earth is attacked.
Number five is set on Earth, with the planet under attack from alien warrior drop ships, which made their debut in the original "Alien" movie. In the process they make Earth look like an incubator while attacking, leaving alien eggs around the humans.
That's when Ripley realizes her dreams have played a role in what's happening and she evacuates and confines herself to a cell, but inevitably she will meet her nemesis face to face again.
Number six takes place on the home turf of the navigator of the ship. Aliens are taking over other plants and Ripley finds herself forced to turn to the dark side in order to save civilization.