Do we want to fight the aliens? No. They have ability to cross the depths of space and and probably comparable destructive abilities (but possibly not). We have to fight them with the technology that we have, despite its limitations.
So let's ask ourselves: what can we field now -- or in the near future -- that could be used to good effect against a spaceborne invasion? Foreign Policy magazine has several proposals now being frantically examined by DARPA. Among them is a missile defense laser system that can be mounted on fighter jets:
From studying footage of TIE-fighters and Cylon Raiders, we know that small alien craft may have the upper hand on even our most advanced jets when it comes to maneuverability. So when our flyboys or flygirls have alien fighters bearing down on their six, let's hope they're outfitted with this under-development project from DARPA that aims to "improve the performance of high energy lasers on tactical aircraft against targets" -- such as an incoming missile -- "in the aft field of regard." It might not win the dogfight, but it can buy us enough time for the cavalry to arrive.
Link -via Glenn Reynolds | Image: DARPA