If Bush wants a good, "just" war, North Korea's has all but dared us to combat. Is Iraq really more clearly a present danger than the confessed A-bomb makers in Pyongyang? I'm going out on a limb and say "no." But disarming North Korea would be bloody and difficult with no upside of oil or defending regional allies (although Japan might feel differently about that). If Saddham would simply "act like Jong-Il," certainly the UN and the US public would fall lockstep into an Iraqi "police action." No one will shed a tear at Saddham's ouster but without an explicit "evil act," like invading Kuwait, a US-led war is only going to make the US look bad. That could well damage the US's reputation for future, more justified, military actions.
Crazily, I think the answer is not war. The US has a whole host of domestic problems that would take several presidential administrations to solve. Wars, traditionally, come to us. There's no need to provoke them.