Here's a really sharp and cogent analysis of the options from Martin van Creveld, a professor at Hebrew University in Jerusalem. He's - how to put this nicely - saner than NPod. But this point could do with more dissemination:
If American spokesmen in particular are to be believed, the declared rationale for attacking Iran is not so much the fear that, once Tehran has acquired nuclear weapons, it will use them against Israel and/or other countries in the region. Rather, they fear, or claim to fear, that nuclear “materials” and/or “technologies” may either fall into the hands of terrorists or be given to them.
Now suppose the U.S and/or Israel does attack Iran.
They succeed in destroying the country’s most important nuclear installations, postponing the moment at which it acquires a bomb by several years and perhaps preventing such a scenario for a long time to come. However, they cannot find, let alone eliminate, every element of the large, well-dispersed, redundant program. In that case, the danger of a “flow” of “technologies” and/or materials falling into all kinds of interesting hands may well become more acute, not less.
Of course the fact this is is utterly irrational to attack Iran at this point does not mean that Cheney cannot talk Bush into it.