I believe there is life in other galaxies. I am really hoping that there is an intelligent species out there somewhere. There definitely isn't enough intelligent ones on Earth.
In addition, I doubt that there will ever be an alien invasion. If they exist and if they attack, it will be because we somehow pissed them off. There is nothing on this planet that aliens would want to steal, at least not now. If some other species had the capabilities to communicate to us and then travel to us, they will need nothing from us because they would have all the technology to synthesize whatever fuel or nutrients they need.
I know the invasion thing isn't the main focus, but I just wanted to add it because movies like Signs and Battle Los Angeles have stupid theories about what aliens might want from humans.