Actually finding WMD makes no difference. Go back to Bush's adress to the nation on national TV where he outlined the case for war. We went to war for four reasons:
1. Saddam's refusal to live up to peace agreement and UN resolutions.
2. We can not afford to wait till Saddam becomes an imminent threat with WMD.
3. Saddam's support of terrorists including Al Qaeda.
4. Saddam's a madman who brutilizes his people and threatens peace in the region.
Actually finding WMD makes no difference to the case for war as originally laid out by Bush. The imminent threat of WMD was a media creation and Bush's biggest fault is letting the media get away with it. The war with Iraq was a just war.