Center channel recommendation

[g859]

So, after finding out that these weren't being used by anyone in the house, I decided to put them to use as the L/R channel speakers. My only problem now is that I have the center channel speaker seen in this picture.

So, for under $500, what center channel speaker would be the best for a room that is about 20' wide x 20' deep x 15' high?

I don't really have a preference about brands, but B&W and Paradigm are my favorites.

Thanks guys!