I already voted by absentee for Edwards, but if I hadn't already voted, my vote was definitely for Obama. When Hillary gave fumbling, lawyerly non-answers, I don't know who she was talking to. When Hillary used dodgy weasel words in response to simple, direct questions about her Iraq war vote, I don't know who she was talking to. When she said we should ignore her past votes, because "we need to move forward," I don't know who she was talking to.
When Obama gave simple (yet powerful), direct answers to questions, he was talking to me. When Obama said he would get us out of Iraq because it's a disaster, he was talking to me. When Obama said that he was against this war from the beginning, he was talking to me.
Since I was firmly for Edwards, I didn't give much thought to whether I'd prefer Obama over Hillary. But after watching Obama's stellar performance at this debate, that sealed the deal. Obama is going to win and he's going to make an excellent president.