Bush will be insignificant as history goes, he's not popular enough to be worth remembering, he started to be seen as a joke by a majority. After this generation no one will remember him, Obama at least has potential. If nothing else he'll be remembered as the first black president, much as Thatcher (for those who don't know, practically everyone in the north of England and most of the rest of Britain despises her) will be remembered as the first female Prime Minister.

I don't think it's fair to judge a leader on how they respond to disasters, in my opinion letting politicians "help" usually ends up being a waste of time and manpower that can be put to better use elsewhere. Not much of what Obama has done has reached me over here but from what I've heard he seems to be working to change the "people are poor because they don't work as hard as me" mentality some Americans have.