I'd recommend David Lee from the New York Knicks as an excellent choice for a center. While small by 7' standards, he consistently puts up 20/10's against virtually every team in the NBA, is not afraid of confrontation, and gives his A game even when his team plays poorly. His contract is up this year so be prepared for a bidding war.
"I've found that when you want to know the truth about someone that someone is probably the last person you should ask." - Gregory House