You can plug any component which has HDMI or DVI output. There are adapters which go from DVI->HDMI, if you use this you will still need to hook up audio cables.
If you hook up the HD cable box with coax, you are defeating it's purpose. Use component or better yet use it's DVI output, then buy the adapter.
If you hook up the HD cable box with coax, you are defeating it's purpose. Use component or better yet use it's DVI output, then buy the adapter.