Well Rio is a fantastic player and played brilliantly again today. Last week he was even better. I can only hope he can continue to play enough games to contribute enough to the team, because he and Vidic continue to show just how good a combination they are.
Smalling is quality and will get better. I think Evans will stick round as 4th choice, he's gone a bit backwards recently but he can still be useful enough. No room for Brown for me personally, though SAF might keep him round.
The Porto (I think) defender Rolando has been linked, as well as Jack Rodwell. Rodwell could fill two gaps as he is currently a midfielder but is reportedly a real option in a back four, or at least could become one in the future.