As for WMD's - Syria has a more advanced program, Iran has a more advanced program. I would wager Pakistan has a more advanced program. And North Korea says they have nukes but might even sell them and tells us to go fry ice! Iraq was no real or immediate threat to us. Sadaam would have loved to be our best friend again. Iraq's WMD's was the excuse to establish a beach head in the war against terrorism.
The Taliban protected Al Queada prior to 9/11, too. The reason we didn't attack the Taliban prior to 9/11 was because we concluded, wrongly, that it wasn't a threat to us. Fortunately, having learned our lesson the hard way, we didn't repeat this mistake with respect to Iraq.
As for the degree of the threat, I would agree that there are other threats of varying degrees. Indeed, one reason for taking action against Iraq now rather than later was to prevent Iraq from becoming the next North Korea. I don't see how allowing Saddam to proceed with his WMD program (even to the point of acquiring nuclear weapons) makes the United States a safer place rather than a more dangerous place. Put another way, you don't cure a smaller malignant tumor like Iraq by allowing it to grow into an even bigger malignant tumor. You cure it by removing it while you can.