I also recall (somewhat dimly) reading one of the books that came out soon after the Gulf War (by Norman Friedman, I think) that Saddam's troops weren't really capable of moving in force into Saudi. If my recollection is correct, many of his tanks broke down moving through the desert to the Kuwait-Saudi border. I'll try to verify that.
In any event, we shouldn't plan on being lucky twice. This time Saddam knows that if we go in, its because we are going to put his head on a pike. Under these circumstances he has no reason to hold anything--including WMD--back.
Thank you - explains a lot. I agree, we will not be lucky twice. When the war begins, Saddam is going to fire off every weapon at his disposal.