I have my doubts about Vucevic, coming from these parts. I just don't think that he is, still at least, NBA ready. It's hard for me to see him making any kind of impact right now. Maybe later, but that's a maybe. He might turnout to be a bust, but it is a second round, so it might be worth the risk.
http://www.nba.com/draft/2011/prospects/nikola-vucevic/Reminds them of Radmanovic. I'm quite sure some of you here wouldn't like that.

And he's a forward, not a center.
On the other hand, we have Benson. Taller fellow, but less weight than Vucevic. Still, on college level he was a very good rebounder, and great defender. Over 3 blocks per game is quite nice, and they mention that besides rebounding game and defense he can play face-up as well. So, that's for sure something that could be worked with. On defense he can be amazing duo with Udoh (when Udoh is played at 4, where he should play), and he isn't bad offensively as well.
http://www.nba.com/draft/2011/prospects/keith-benson/I would be for Benson. But, we definitely need someone at center position, either tonight, on via free agency.