Carolina:
I have T5s up front, an M5 center, M5s as side surrounds and L5s in the rear. I would go for an NAD receiver: more juice than the Marantz. If you can go with a vertical center, you might try M22s as left and rights, M2 (or 22) as center, and M2s and surrounds. This would be a killer system.
And I'm not the only guy here who advocates vertical centers. Horizontal centers are a compromise: most folks don't have room for a vertical center (or won't tolerate it on top of their TV) and most manufacturers don't have the drivers necessary for a properly designed horizontal center. You need a 3.5 or 4 inch midrange to run below a tweeter to keep the horizontal center a reasonable (under 8") height.
