Comment WDTV Live is the best! (Score 2) 420
Another happy WDTV Live user here. I have this exact model, purchased in November 2011:
www.amazon.com/Live-Media-Player-Wi-fi-1080p/dp/B005KOZNBW/ref=sr_1_1
Just set up a SMB or NFS share on any computer you want, and this device will play ANYTHING you can throw at it (including flv, at least in my experience). Has 100Mb ethernet, N wifi, HDMI out, optical out, USB port, and a remote.
It will talk to a "media server" if you really want it to (DLNA, etc), but I've found a simple file share is the way to go.