Well just to put a different spin on this; there is one school of thought that thinks it is far more likely that IF we did encouter another species from far far away in the sense that they travelled to us, that they would actually be quite benign (one of the main champions of the theory being Carl Sagan).
This is because it is assumed (and we can only have an earthly perspective on this reasoning of course) that any race that manages interstellar travel will have done so through global co-operation in many aspects, such as economy, peace-time etc. In other words, if we as a planet were to ever succesfully start interstellar travel, it will only happen when global resources (materials, man-power, money etc.) are no longer being used on global-wide things such as war, and the idea of an 'economy' radically changes; as such an task would only be successful if it was a global effort. And when this point comes, we would probably consider ourselves pretty friendly I imagine, and using the same reasoning the same would go for other races.
Of course if an alien race visited us now, we would probably be considerably less friendly. So the best chances for two civilizations meeting are those who are both technologically advanced beyond a certain point.
I just thought I'd add that perspective to the mix.