What is the definition of a Civil War and why does it matter?

The networks are agog about whether Iraq has lapsed into a civil war. Presumably, this is a part of the continued effort by many in the media to oppose the Administration's policy there. The data suggests that something has changed in the last few months - civilian deaths and evidence of ethnic cleansing are increasing. But there are larger questions that should be asked. Afterall, we have interposed ourselves into places with civil wars before.

The questions I would ask include:

1) What is the best way to confront the Islamofascists? Was Samuel Huntington right in that we are engaged in a clash of civilizations? If so, how do we respond to that clash? Now.
2) What would be the effects of pulling out versus staying in the immediate and long term for US foreign policy? Clearly the withdrawal from Vietnam has had long term negative implications for our foreign policy. But one wonders whether had we stayed and lost more Americans in the commitment in Vietnam whether that would have been more disastrous. Foreign policy is a set of tradeoffs but from the clear comments made by our opponents in Iraq, especially Osama, the Vietnam experience and our experience in other venues like Somalia and Yemen suggest that our opponents believe if pressure is applied we will cut and run.
3) If we decide this is a civil war, what should we do about it? Can the country (US) potentially agree to more troops if they are needed? And equally important, if we decide it is a civil war and decide to cut our losses, what happens next?
4) Finally, if we decide that our policy should be to stay, how do we enlarge our circle of friends?

I am not sure why all of a sudden the talk of civil war has risen to the height that it has. Clearly, we are in an unstable region. But also clearly the Iraqui people have three times asserted that they want to figure out how to make this new system work. We've got to decide whether this is the place we need to make a stand against the fanatics who are precipitating the "civil" part of the much larger war.

The talk of a civil war is really a red herring in my mind. The broader questions of how we effectively negate the efforts the the Islamic fundamentalists is more central to our long term interests.