I have just finished reading the Episode One novel. It explains it all a lot better. Obi-Wan was against Anakin being trained at first but in the final battle with Maul Obi-Wan finally gets in touch with the living force to defeat Maul and becomes more insightful. When Anakin destroys the droid command ship (which in the book is much more the will of the force than a kid saying 'oops') Obi-Wan, wiser and more understanding following his master's death, believs that Anakin is the chosen one and sees that Qui-Gon was right all along. So, it wasn't put across too well in the films but having read the book I appreciate their relationship a lot more, although you shouldn't have to read a bookmto enjoy a film...