The anti-war red herrings grow tiresome today. ("But Saddam will be more inclined to use a WMD if we do invade!" Yes. And the likelihood of his using a WMD now is therefore tolerable? And we won't be able to disarm him quickly enough to reduce the likelihood to zero? These are pseudo-inquirers, most of them (not all). Under almost no circumstances would they accept that the U.S. should invade Iraq. Therefore, they aren't engaged in genuine search for the right answer.) Here's the case, free of red herrings:
Put the chance of Saddam having a nuclear or bio/chem weapon smuggled into some large American or Israeli cities and exploded at, say, 2%. That's a lowball. It's intolerably high.
Assume that the American casualties in an invasion will be far lower than the casualties we would suffer in case he managed to smuggle in and explode those weapons. Assume that the number of dead enemy innocents will be lower, as well.
Note that we will be liberating oppressed people by invading.
It seems like a good case for invading, to me.
In other words, there is a treacherous Arab tyrant who poses a threat, who hates us and Israel, who screws his people, and who can be taken out without catastrophe. That's enough.