Currently, slimcenter supports only mp3 streaming.  Request ogg support in addition to mp3 streaming support.  ogg streams can consume less bandwidth (50kb for ogg versus 128kb for mp3) with the same relative listening experience.  Uploads from cable/dsl are usually between 128kb and 384kb - and with all the other applications competing for this bandwidth (VoIP/Distributed Networking) every little bit helps.  Ogg is also free without licensing fees so that is a plus.