Uhmmm....I supposed we'd be in a world of hurt.
But if they are more advanced technologically (as far as space travel is concerned) than we are, they should be able to get to us first anyway. It should be easy to find Earth with all the radio emissions we've been putting out. If we find them through our own efforts and they can't get off their own planet (or out of their own system), all we have to do is avoid them. If we are evenly matched....we'll just see who eats whom for breakfast!
I'm not familiar at all with the SF threads here at FR.
Thanks Overtaxed, I was forgetting about all that....You'd think by now someone probably already knows about us...