Your receiver really has nothing to do with being able to watch HD on your TV. If a receiver has an HDMI connection, then you can connect everything into it and then into your TV, but this is more for convenience. For HD video on your TV, you can connect a cable or satellite box or a DVD player directly to the TV using separate inputs. Neither the cable box or DVD player need to connect to a receiver before the TV as both can connect directly to your TV using component or HDMI if equipped with it. If you want 5.1 audio, then these can connect to your receiver by either using the optical or analog audio connections.
I have a Sony STR-K750P Reciever that I was wanting to connect my surround sound with. This receiver doesn't have an HDMI input or output. My question is can I hook this reciever up somehow with the audio and still watch my TV in HD?