Respectfully disagree. I am coming from the POV that if an intelligent alien species has the technology to travel for thousands of years and/or at near light speed, overpowering current human technology would be an afterthought. You can't do this with any technology we currently have, nor are we anywhere close. Harnessing the required energy alone is well out of reach right now, let alone storing and using it for propulsion. Hell, we are still relying on a barely controlled explosion to break earths gravity and reach space.
Whether they wanted to or not is another question of course. Fun to think and debate about for sure.
EDIT: You ever heard of Dr. Michio Kaku? He frames this thinking better than I am capable of. See the following for more, basically his contention is the same: Any race capable of reaching us would be so vastly superior that we would be like ants to them.
http://bigthink.com/ideas/24198
http://discoveryenterprise.blogspot.com/2010/10/sci-fi-science-alien-invasion.html