In my opinion, there are two ways a President gets things done. Conspire and Inspire.
Conspire: Barack Obama has plenty of experience in putting together coalitions and voting blocs as an organizer in Chicago at the grass roots level, in the Illinois state senate and now as a U.S Senator. And that is the weak side of the two for him. It can be addressed by the proper choice of a VP... and since the VP is the one that spends the most time on Capitol Hill, the VP is the person that needs that experience the most.
Inspire: This comes down to the ability to fire up both legislators to pull things through congress and the general public to push things through congress. Barack Obama is without doubt the most dynamic speaker running for President. He is, IMHO, without doubt the one best able to inspire. Do this as an experiment: Go to YouTube. Find speeches by the three remaining major candidates. DON'T pay attention to the speaker. Pay attention to the audience. Remember, these are people who already support the speaker. The difference in the reactions of Obama's crowds is palpable. This man can create excitement.
As such, the major argument people put against him, lack of experience, doesn't wash with me. He has the tools.
It's just a matter of whether or not you believe he will use them in a way that is beneficial for the country. Since I believe he will, I support Obama.
I'm not terribly anti- Hillary Clinton. But she doesn't make me feel like she is anything other than a lesser of evils. Barack Obama makes me believe in America again.
John McCain is at least a person whom I respect for some of the things he went through due to his service to the nation. I respect him for being willing to publicly disagree with someone in his own party. But I wouldn't vote for him over Hillary.
I have zero respect for Bush. ZERO. I look forward to the end of an error... or rather, the end to a presidency that was stolen in the first place.