What happened on September 11 was, to Americans, much worse than Pearl Harbor, and most people understand that the stakes may be much greater, because of the new kinds of weapons available to our adversaries.
This will not be a Marquise of Queensberry war, except insofar as we perceive it to (temporarily) be in our strategic interest to make it so. While we aren’t officially tipping our hand now, Afghanistan is surely just a beginning, and when it is over, the Middle East will have a much different landscape, both geographically and politically. We may restore the Hashemite Kingdom to the Saudi Peninsula, we may restore the Ottoman Empire, or come up with some entirely new order there, but the current way of life there was doomed by bin Laden two months ago. For this, the people of that region may ultimately be grateful, but the outcome will not be the one that he desires.
We will suffer casualties, perhaps greater than any war in our history, both military and civilian, and we understand and accept that, but we will endure, and ultimately, we will prevail.