I agree that Carr has a lot of potential. He is kind of stuck in the same position as Joey Harrington (even drafted the same year). But, with the line as poor as it is-it is something to consider. I don't think that Vince Young has that great of arm-he doesn't have good enough touch on the ball to be the #1 QB in my mind (I figure New Orleans will draft Leinart).
But, he has the ability to get away from the defense to by time to find the open man-which Carr doesn't. Plus, Bush is not a power runner-and without a good line a speed RB is not much good. But, he has a ton of talent so you never know.
I would probably draft Reggie Bush #1 unless someone gave me something good for David Carr. But, I would make it known that I was interested in trading him if I was Houston to see what offers I got before making a decision.