At least if we do go to war with N. Korea, it won't just be Americans on the front lines. Either way, I think the US wins on the N. Korea issue.
1. If the N. Koreans give in, they will have to disassemble their nuclear reactors and anything that can be used in the future as bargaining tools. We'll probably end up sending more aid if this happens, but it's not like we don't already send a crapload of aid to the rest of the world.
2. If N. Korea starts a war, then the US won't look like an aggressor, but merely defending S. Korea. Can you say regime change? I believe S. Korea will take the hit on casualties, the US will take the hit more on cost.
Either way, it will lead to eliminating this threat.
On a side note, if we end up going to war with N. Korea...I think it will be very long and bloody, it won't be a cakewalk. Even if most of N. Koreas million man active army (6-7 million reserves?) isn't really trained that well, the asian armies have been known to fight tooth and nail.
If I lived in Seoul, I'd move