My guess: I think that Clinton will win the nomination
Add to all that that Clinton will push for the large Democratic delegations from Florida and Michigan to be seated. If she pushes hard with legal action, it could really produce hard feelings among African-Americans. The more that it seems today that Obama is going to win, the more his supporters will be angry if she gets the nomination. It will be a bloody and difficult win, but the Clintons will do what they can and conditional on Texas, I give her the edge.
All that said, I also think that Obama would be the easier candidate for Republicans to beat in the general. He is the most liberal member of the Senate, and his record will just be too much to defend. Take for example, his opposition to renewing FISA because it would allow us to spy on conversation where foreigners are talking to foreigners. I think that will be hard to explain to people.
UPDATE: I have just come across a poll for Texas and it shows that Obama is in the lead. Obama is ahead 48 to 42 percent. "Hillary Clinton leads Barack Obama among self-described Democrats 47% to 42%. Obama leads Clinton among self-described independents and Republicans 24% to 71%." On the other hand, I wouldn't put too much weight on this right now. The main reason for this is that I am becoming more convinced that she will take Wisconsin. If so, I think that Clinton will take Texas along with Ohio and Pennsylvania. Obama will be edged out because of the super delegates and the seating of the Florida and Michigan delegations.
UPDATE2: Several new polls give Clinton an average of a double digit lead in Texas.