I would make a comment about this being a zombie thread, but I'm above that sort of thing.
threads are hereby immunized from accusations of zombitude.
PS, anyone who's caught up w/S1, here's the part that still gets me:
I had the episode still on my DVR where Shane describes finding Rick in the hospital, listening for a heartbeat and hearing none, and reasonably concluding that he was dead, and leaving him behind. He hears gunfire in the background, but said it wasn't loud enough to have muffled a hearbeat.
I replayed that scene, and Shane was right - the gunfire wasn't loud, and he still should have been able to hear a heartbeat. Also, when you put your ear to someone's chest, you should be able to feel a hearbeat as well. I think Rick was actually dead at that point, and for whatever reason (unique genetics? maybe some medications he had in his system at the time?), he resurrected via the zombie virus without becoming a zombie. Now that would be a radical plot twist!
The biggest problem would be ammo supply. Every soldier would run quickly through his basic load and the Rodney King riots teach us that the National Guard doesn't keep that much on hand for a Red Dawn/Battle:LA scenario. And even with one shot one kill you would just get one city block full of zombies and from there its hand to hand with swords being in short supply. Pure physical fatigue against an unexaustable enemy would soon enough see any small army overwhelmed.
What about the ammo/gun supply in private hands (50% of all US households own a gun), gun stores, sportings good stores, Wal-Mart, etc? And all projectile weapons, from crossbows to rocket launchers, need to be taken into consideration. The survivors would have everything produced by society at their disposal.
How long does ammo last before it goes bad (does it ever?) My hunch is that the ammo would be less of a worry than the food supply. Even canned goods won't last for years.