good choice on the dv400. upscales to 1080p for future display upgrade, and if your current tv panel is good at upscaling, the 400 can output native 480i too, which is lacking in the hd870.
in fairness, the hd870 looks good on paper too. 14-bit 108mhz video, s-video out in addition to hdmi and component, plus EZ View... and 110db s/n 100db dynamic range on audio, with both coax and optical out.