One of the challenges of making your space above the mantel a media center is that much of the time, you will have a big black rectangle. Be sure to get something like a roku box, and hook it up to your google or Facebook photos for a screensaver. Another challenge is it will be much higher than you would otherwise hang a television.

Now, for your selection of media. You may want to leave flexibility for resale. Think about the intercom systems from the houses from the 1960s and '70s. I'm not a technorati, but this brand of electronics are, imho, http://www.bang-olufsen.com/. My husband, who is far more technically inclined that I am however, would suggest Samsung for the flatscreen, and relies heavily on cnet.com Here's their assessment for home-surround sound systems: http://reviews.cnet.com/2719-7612_7-269-6.html.