Honestly, just watch Independence Day. It's basically exactly the same. Except they don't use a virus to bring down the aliens. Just one teeny missle does the trick.

But if you really want to know...aliens disguise their invasion as a meteor shower. The "meteors" that hit the Earth are actually invading alien forces. I can't remember for sure, but they attack at least 20 major cities worldwide. The human experts believe that the aliens are taking over Earth and irradicating the humans so they can take our water.

The humans absolutely get their asses kicked--Los Angeles is more or less completely taken out in the span of a day. It seems like the other major cities fates are similar to Los Angeles. The movie follows a group of marines whose mission is to get to a police station where civilians are and escort them to some kind of safe zone. Somehow they discover that the alien ships that are kicking their asses so bad aren't manned and are just drones that are being controlled by this massive control center underground. The 6 marines procede to find this control center (think of it as the Pentagon) which is inexplicably guarded by very few aliens and are able to blow a little bit of it up. The control center then rises from the ground and once it's above ground, ONE missle is shot at it and the entire thing blows up. After it blows up, the ships fall to the ground and are destroyed and the alien ground troops retreat.

We're then treated to a rip off of both Independence Day and Black Hawk Down as the marine commander says something like "instructions on how to bring down the ships are being relayed around the world and all the ships are going down". Like at the end of Independence Day when they discover that the ships can be taken out by blowing up their primary weapon and then all the ships over the other worldwide cities get destroyed because now everybody knows how to do it. The marines are then ordered to rest up, but since they're so tough they decide to resupply and head right back out again. Think of the end of Black Hawk Down when Eric Bana, rather than resting, decides to head right back out into the shit again.

In the middle there's some really crappy dialogue, but the main point of the human interest stuff is that Two Face is a Staff Sgt whose last mission didn't go well and many of his guys ended up getting killed. The current marines under him don't trust him, but in the end he decides to take out the alien control center by himself while his marines got to safety but his marines suddenly respected him and then decided to help him take down the control center.