Just found a remote control for dlna players like the Philips TV for the Nokia N900. Works great! Now I'm also able to create playlists and control the volume of the television using my n900. Works for music and video. Photos did not work for me.
Apparently there is also a pc version, but I did not yet try that one.
http://my-maemo.com/downloads/search...=DLNA%20Player (only version 1.5 worked for me).