Now that you have your A/V receiver, speakers and the screen now you need something to play on it.
When it comes to selecting the components, options you have and might need are; Blu-ray player, CD player, Tuner, Set Top Box (STB), Personal Video Recorder (PVR), Home theatre Personal Computer (HTPC), Games machine, Almost anything that can play a video or music, with the right connections can be connected to your home theatre system.
Here is a few choices for your video source. Panasonic PVR, Sony PS4, apple TV and a Oppo Bluray player (at least for now.)