The American Magazine Fortune posts that the conflict with Iraq consists of three truths for the American people.
First, when UN inspectors left Iraq in 1998, Iraq had large amounts of weapons of mass destruction left at his disposal, even though the UN inspectors spent 24 hours a day burning these weapons in incinerators. Even then, Hussein was well on his way to developing nuclear capability - something that would change the entire balance in the Middle East.
Second - since the inspectors left, many Iraqi defectors have told stories of Hussein pushing his efforts in achieving more weapons of mass destruction, despite the UN mandated sanctions which made it difficult for him.
Third - the US realized a painful truth. It has enemies that would very much like to harm it, and that can do that.
Faced with these three truths, it's obvious why the US wants Hussein out of the way. And there's probably nothing the rest of the world should, or can do against that.