Your comments on the UN seem rather silly when you look at what the UN actually is, you do realise that every country in the world is part of the UN apart from Taiwan as most countries don't recognise it as a seperate entity to China and also Vatican city isn't a member. This means that Iran has an obligation as a member of the UN to let those inspectors in anyhow. Quite how the UN can overestimate themselves when the UN represents pretty much the entire population of the planet I'm not sure

Perhaps you're confusing the UN with the permanent members of the UN security council which are Russia, USA, UK, France, China but even there it's hard to suggest that 5 countries with such different political regimes and goals can also be a bad thing, the only thing I will say on that is that muslim states are under represented in the permanent security council itself.
Nuclear weapons aren't something you can just ignore so to put them in the hands of someone who wants to whipe a planet off the face of the earth is insane. I don't particularly like George Bush and feel he's somewhat of a war monger himself but at least even Bush, as dumb as he likes to make out has the sense to realise that nuking somewhere is bad - the Iranian president doesn't seem to have that equal understanding.
Countries that are currently nuclear capable generally realise that nukes are a bad thing and just about every country that has them is working towards disarming them as far as possible. The problem is nukes exist in these countries as a deterrent to other nuclear capable countries, that's why disarming them is already hard enough because you have to slowly phase out the weapons in a way where every country involved feels safe that they're not being tricked into losing their nuclear capability whilst another remains nuclear capable. If you let a country like Iran become nuclear capable then you only complicate the situation much more as their goverment doesn't understand what an equally measured response is - i.e. Iran will claim they need to keep their nukes in case Israel attacks them even if it's with conventional weaponry and in revenge for Iranian funding of a terrorist attack inside Israel and hence Israel will refuse to disarm their nukes in case they need to counter attack.