Imagine that the Dollar is doing badly and the US economy is performing a slow slide. The major thing holding the dollar up is that national and transnational organisation need large amounts of it in their reserves. For instance, all oil-buying countries need dollars because OPEC (the Arab alliance of oil producing countries) sells only in dollars.
Iraq switched to selling in Euros instead. It looked like a bad move financially for him, but has looked much better as the Euro overtook the dollar. Apparently OPEC is considering following suit. Now, imagine the effect that would have on the US economy as everyone has to buy Euros instead of dollars - a 20% slide would be the best they could hope for.
Maybe the Gulf War is all about making sure that this doesn't happen?
(note, this doesn't mean I think that regime-change isn't necessary, but I'm not foolish enough to think that Bush's motives are aligned with mine.)