That's enough doses to treat a quarter of the UK's population, apparently. From what I know, Tamiflu is effective in lessening the symptoms of flu, including the avian flu. However, I don't think it will help to stop the spread, so targeting it at the population in Asia before the virus spreads worldwide probably won't help.
I think this is probably a good idea, and I would definitely support the US ordering more doses of the drug. However, it seems unlikely that it's possible to manufacture enough to treat all the Americans who will be infected, let alone everyone everywhere. Perhaps that's why the government here isn't buying the drugs. Still, I'm a little concerned that apart from the CDC I've heard very little out of the government on this matter. If a pandemic happens, it is probably going to kill more Americans than terrorists will, so where's all the hype about the War on Flu? Grant money for researching faster vaccine production? Offers to pay China if it will slaughter all its fowl?