I agree that the UN is worthless and we should not be involved with them. But the common alternative proposed by those who oppose our invasion of Iraq is that we should have let the UN handle Saddam diplomatically, so I think it is valid to point out that the UN had been issuing resolutions for over a decade without making any progress.
Also, it wasn't just UN resolutions that Saddam was in violation of. He was continually ignoring the restrictions that the US had imposed after the Gulf War (i.e. no fly zones, no drive zones)- restrictions which we had enacted in order to protect the Kurds in the north and Shia in the south.
Thank you. 