To me the real question is this: Would you trust Saddam Hussein without sanctions of any kind to run his country? My answer is: hell no. That would scare the shit out of me, especially since they have openly stated that they were pursuing nuclear, biological and chemical weapons programs before the 1991 Gulf War.
So, if you accept my answer, then what's the solution? You either have to: a) Keep sanctions on that kill millions of Iraqis every year because of not enough food and not enough medicine or b) get him out of there. To me, b) is the best answer by far. I'd rather they just send him into exile or something, but he needs to leave. Yes, a war will have civilian casualties and that is obviously bad, however that number would be less than the number that die every year due to the sanctions I would bet.
About North Korea, no one has yet stated the real reason why the US doesn't want to attack them. Yes, on a cost/benefit basis North Korea isn't very appealing, but the main reason why they cannot fight North Korea is because of China. If you know the history of the Korean Peninsula, it is basically that after North Korea virtually took over South Korea and the allied forces (including the Canada and the US) helped push North Korea back, they actually took over all of North Korea as well, all of the way up to China. China didn't want a western presence that close to its borders and so it sent in troops and pushed the allies back to where the border is today. So, China didn't, and still doesn't want a western presence right against it, and so if the US took over North Korea they wouldn't be able to occupy it to ensure a favourable government was instated after the fact.
Finally, a couple other points:
i) The person who pointed out that the US has the largest stockpile of nukes, etc. was wrong, that's still Russia by far
ii) The US is the only country to use a nuke in a war, but that was to end World War II, and no one even really knew about the radioactive fallout. Are you honestly going to bitch about that?
iii) You can't reveal intelligence information without compromising the methods used to gather it. Powell's speach was supposedly the biggest public de-classification of information in the US' history, so give them some credit.
iv) North Korea would never turn into a Vietnam, because the US wouldn't fight a war with all of the political strings attached to the Vietnam war ever again. A Vietnam commander was quoted as saying after the Gulf War that if they had been given as much leeway to just bomb anything in sight as they were during Desert Storm that they could have taken over Vietnam in a week.
v) The oil argument. Sure, the US would like to have control of oil, but Kuwait and Saudi Arabia are totally in debt to the US and constantly trying to get on their good site. This is not to mention the fact that they are the biggest oil producers right now. So, I don't know if controlling Iraq for a few years would justify the billions that will have to be spent on this war.
Thanks!