You all witnessed how long it took for the National Guard to get into New Orleans in large numbers. The National Guard takes time to muster as people are diverted from their daily lives and then organized -- it makes sense that they would take days to respond. You can argue that they should have been pre-deployed. I live in California, and I would hope that we'd have a standing force of National Guard ready if we had pre-warning of a magnitude 7.8 earthquake coming. Yet, there is no doubt that active military can move faster than National Guard simply because they are already actively deployed.
It is obvious that the US armed forces are being spread too thin. The mess in New Orleans has to be partially blamed on the bulk of the mobile US Armed Forces being deployed in Iraq and Afghanistan, and the federal government not taking the steps to make sure that we have enough military to take care of domestic issues should they occur. Now, to me the reason for this is obvious: recruitment in the military is down, and we do not have a draft. If we did have a draft, I am sure political will would start to wane. So, we have ourselves a conundrum that leaves a gaping vulnerability. A draft alternative would be truly domestic and full time deployed National Guard which can't be tapped to go abroad.