Don,
The UN as we have it today is not perfect, not anything near. It was not built to fight terror. But the US can change it. They are the strongest nation and after 9/11 almost every nation will be glad to follow. The attack on London is another opportunity to gather the forces of the free world. In my oppinion the US has the historical chance to gather all free nations including Europe, Russia and some moslem nations under their lead.
However, the US itself would have to work with the other nations under the frame of the UN. This means that other nations are not just auxiliaries playing their role in according to the script written in the Pentagon.
So the question is not is the UN perfect or can it be renewed. The question is is the US willing and able to give the UN this chance.
P.S.: I'm not happy to say that, but Europe would be more than happy to follow an American leader, like we did in the Reagan area. It is not jealousy or anti-Americanism in Europe that finished the union of the western world.