The AVClub is quickly becoming one of my favorite sites to visit. One of their older articles talks about the various ways humanity is doomed in different movies. Regarding the alien invasion motif:
One thing is certain, though: In the unlikely event that Earth is invaded by E.T., resistance will indeed be futile. Says Shostak, “If they have the technology to come here and try to take over, it’s going to be Bambi Meets Godzilla. And we’re Bambi.”
See, you even have scientists saying it now.