When I install Linada I can stream media from my PC but, so far as I understand it, the app is also supposed to detect the PC as a media player and control play back there (Linada isn't a DLNA server but it's description says you should be able to use it to control playback on a remote device).

For some reason the phone won't pick the PC's DLNA client up (although the router currently lists the PC has having both a UPnP MediaServer and a UPnP MediaRenderer Perplexed). I think it may be something to do with the way WP7.5 operates on the network?