Is coaxial from HD cable box to HDTV needed when connecting component cables from HD Box to HDTV?
Two connections are okay as long as you select the one that gives you the better picture. Be sure to select the HDMI input on the HDTV. The other cable can stay for when someone accidentally changes the HDTV to channel 3 when turning it on. Just be sure to set it back to the HDMI input for the best picture and sound. If you want to use the HDMI cable with a cable company or satellite company box and the antenna input to the TV for an antenna you can do that too. This allows you to watch local channels in your area depending on the capabilities of the HDTV tuner and the gain of the antenna as well as its orientation to the local stations. This is useful when local stations have programs not carried by cable or when cable or satellite service is not working.