Personally, I'm not too worried about North Korea, but Iran is being exposed in ways it wouldn't have otherwise. Thise who think that Iran is not a big deal just aren't paying attention.
What do you want... a unpredictable madman in your back garden or a religuous extremist on the other side of the street that is noisy but predictable.
While the current Iranian leader might seem a little on the agressive side, he got far more experience and political feel than Khatami. He holds (and has held) some fairly high positions in various organisations, and before he became president he was major of Tehran (which is considered the 2nd most difficult political position in Iran). The amount of anti-Israel screaming is often directly related to internal poll results (he sees himself as a populist).
About the weapons program... don't forget that the supreme leader is AGAINST nuclear weapons (he made an official statemen about that).
Getting in trouble with Iran will more likely result in a reaction of North Korea than the Iranians themselves doing something nasty... China will have a reaction... and the most effect has been proven to be when they untighten the leash on the DPRK.
And the biggest unstable factor at the moment is Pakistan... every day more information is leaking out that suggests that the government is actively helping Al Qaeda. Musharraf won't take action against this because when he does his career is finished (in a quite permanent way).