Why is my HDMI hookup not looking like high def?

HDMI is a cable interface and does not in itself produce high definition signals. That is the case for any and all HDMI cables, regardless of the cost. To get an HD quality image, you must first get an HD source.

Bluray players are HD but they will only produce HD quality if a Bluray disc is being played. Playing an SD DVD in a Bluray Player does not produce HD quality. That is the case even if the image is up-scaled to an HD format.

Likewise, playing a DVD in a regular DVD player does not deliver HD quality even if the DVD player up-scales the signal to an HD format.

If the source is an HD one, it is worth checking the settings to make sure it is set up to output HD rather than SD. Some models can be set to output only SD signals. Also, make sure the television itself is HD. There are a small number of "HD ready" televisions that will accept an HD signal but will reduce the resolution to suit its own low resolution screen.