Apple TV needed in my system?

Am looking at the following entertainment set-up for the den downstairs:
- Panasonic Viera TC-P50G20
- Sony BDP-S570
- Yamaha RX-V667

We've modded an older X-Box, so that streams music / videos from the external HD's hooked directly to the iMac that is upstairs... the new TV & DVD player will go downstairs, next room over from the Apple Airport Express.

So, first question is this: with the abilities of the Sony DVD player + that of the modded X-Box, is there anything that having an Apple TV would bring to the picture [pun, what pun? ] - any benefit?

[ http://www.sonystyle.com/webapp/wcs...10151&langId=-1&productId=8198552921666077660 ]

I guess though that there may be some issue trying this [not using Apple TV] since there is this conflict? However, we've been able to stream content via the modded X-Box to a current TV... but won't be able to via the Sony?
http://en.wikipedia.org/wiki/Digital_Audio_Access_Protocol [iTunes / iPhoto]
vs
http://en.wikipedia.org/wiki/Digital_Living_Network_Alliance [Sony DVD player]

PS - of the above items, are there better quality and/or improved versions, in similar price point?