I have the Western Digital HDTV Media Player (small black cube-ish looking thing). Its great and I love it. Pic and sound is great.
Can be a little slow to load up sometimes when you connect a large drive via USB. It also seems to revert to the optical digital out for DTS rather than the HDMI for some reason so if the files have DTS then you'll need to use an external decoder/amp etc with an optical input.
Also, don't put anything on top of it, the little thing get pretty hot too...