You can install Media Center on something like a tablet and as a client you can connect it to another Media Center server running on a device in your network and you can either use the client Media Center to control the server Media Center or you can stream your media from the server to the client Media Center.
My example is, I have a Media Center server running on a Windows desktop PC, and I have a Windows tablet as well. So while Media Center is running as a server on the desktop PC, I have Media Center installed on the tablet and I connect it (via Media Network) to the Media Center server so it becomes a client. The Media Center client on the tablet can be now used to control the playback of the server Media Center or I can set it to stream from the server to the client Tablet.
So you don't need a physical remote control for that, it's optional if you want/need one.