Chennai should be reasonably strenghtened by the additions of Muralitharan, Balaji and Albie Morkel, who should never have been excluded in the first place. Kallis returning for the Royal Challengers should give them further batting depth, and seeing how well experienced spinners have been doing so far, Kumble and Murali should play key roles in their teams' fortunes. I reckon Chennai will nick this one, though, by the virtue of having a way better batting lineup.
Watch out for - Albie Morkel. One of my favourite ball-smashers.