I think that the reason America takes so much flak for things in the international sphere is simply that America *does* interfere, be it economically, diplomatically or militairily. Whether you see this as good or bad is a matter of opinion but for some people at least, it's always going to be a bad thing.
Additionally, as far as I know - a lot of that money for AIDS is basically to encourage absistence and other ineffective, religiously motivated means. It does rather smack of throwing money at the problem, which history should demonstrate doesn't really help much.
And it's hardly surprising America gave more money than anyone else to Afghanistan. It was America that bombed it back to the Stone Age.
I'm not one to criticise Americans for the sake of it and I certainly don't hold individuals responsible for the actions of their countries. I certainly think Tony Blair should actually spend some time in prison for willfully ignoring the will of the people that elected him to represent them (well, not directly elected but still) but I think that America has done rather dubious things of late but look on the bright side - everyone just wants to have the wealth, power and influence of America. That's at least one theory as to why the Middle East hates the US.
But anyway, I'd say that off the message board and in St. Andrews one is somewhat more hard-pressed to find anti-Americanism. Mainly because of all the Americans about