Assuming, of course, that we want to start a war with Iraq. I don't think that's what's in store. Instead, I think we're going to take out Saddam and a few of his closest friends.
The difficulty with taking him out is that he's always on the move, and has numerous look-alikes who travel around the country to throw off possible attackers.
However when it comes to actual military planning stuff, Saddam has to be in the room with his generals. To find Saddam, you watch the guys he has to meet with, and take him out when arrives. If nothing else, Afghanistan has shown that we can make these short-notice, pinpoint attacks. The real key to finding out would be to count the number and type of planes in the no-fly zone.
And the best way to force a meeting is to get word out that we're planning a 1991-style raid into the country.
Bingo! When our operatives on the ground tell us Saddam's generals have all converged at one spot, chances are we'll be able to get Saddam, too, in any attack on them. If not, it's always good to take out their top brass. I would hope we would use a rather powerful nuke in this situation, particularly if the site isn't too close to a large city, just in case the meeting is scheduled to take place 90 feet underground.