Invasion!

So then, to promote debate: What would we need to do either before-hand, or after their forces hit Earth to save our butts?

Beforehand...early detection. Need I remind you what happened to the Protoss Homeworld because the Protoss got caught napping ? Even then, detection won't help much except for a slim chance to prepare. After, well the civilian population is pretty well done. Other than what few make it into underground bunkers under military protection, the rest won't last long. Civilian ammo would be useless, grenade and rocket launchers, along with flamethrowers and armor piercing rounds would be necessary. In short it would be a military operation, and the draft would be in effect and locally enforced. If you could physically hold and fire a weapon you were in. Given the power and resources of the zerg, the only chance would be destruction of the Overlords. Short of that, it would just be a matter of time.

This is the kind of response I wanted. So: Promote the air force. Target overlords. Once the zerg are confused by their lack of control, mop them up? When zerg forces run out of control, do they run amok, or freeze up? Would killing the overlords create a more dire scenario? I see another problem in their hatcheries. They reproduce much quicker than humans can. How would we get rid of those? Nukes would be more harmful to us than to them, after all, they can survive the radiation in space unsheilded, and that's worse than fallout, as far as I know.

Not exactly what I had in mind, but hey, if the shoe fits...

I think it'd be over pretty quick myself. The overwhelming argument on the other board was: Do we have more bullets than they have zerglings? I prefer playing Zerg myself, but Protoss are definitely the most powerful.