I agree with all of the above. The opening scene didn't make any sense to me at all, either.
I actually found the "engineers" more creepy than the aliens. (BTW, if they're a DNA "match" then why are they ten feet tall?)
I have to assume the engineers were creating the aliens to battle the predators, otherwise AVP doesn't make any sense. But then, why are the predators using Earth as a training ground? And why don't any two of the aliens look like each other anyway?
And, did anyone learn anything from the epidemics that wiped out the Incas, Taino, Plains Indians and those people in "Medicine Man", not to mention the bubonic plague and the 1918 influenza? Viruses bad. Strange viruses really bad. Yeah, I'll take my helmet off on a planet that we landed on 15 minutes ago. Sure.
