Just went HD with comcast and picked up their HD-DVR box. Damn thing has more access ports than my audio system...dual firewire, HDMI, USB, Ethernet, along with the standard optical, component videao and audio jacks. Dunno if the firewire jacks are enabled tho.
Two tuners are nice too, letting me watch on channel ad record another, or record 2 channels, swapping back and forth to watch without interrupting recording.
Drive size seems a bit small, tho..and I've just started playing with it. I envision it to just record shows I miss until I get a chance to see them, and am not planning on using it for long trm storage. Comcast plans to add box supported picture in picture in the future, eaning even those sets that don't have PiP would be able to use it.