Networking & wireless: Fairly complex question

Fairly complex question

I recently updated to AT&T Uverse. When the installer came, he messed with my network quite a bit. Here's how it looks now: One main gateway, to which my wireless-n Netgear router is connected. That Netgear router has two PCs, one of which is the media server PC (running Debian), and the other the main family computer. There is another PC connected via PowerLine (i assume to the main gateway). In addition, there is a Xbox 360 on the DVR, which connects back to the main gateway. Is there any way to set up the network so that I can stream stuff from the media PC (which is on the Netgear router) to the Xbox 360? Thanks for any help in advance!