HDMI vs. Component Cable

I currently use AudioQuest component cable for my video. All cables used are AudioQuest, the problem is how do I benefit and compare the two types. My system is a BK507 AVR, Denon3910 DVD, Mission Electronics V6 series Surround Sound, Velodyne DD10 Sub and Monster Power HTS3000. All cables used as stated are AQ highend AQ. My dilema deciding to change my component from my AVR to my HDTV and go with an HMDI. What about from my HD Tuner what cable do I use there? I'm confused?

I got a bit confused from your post. In this case the tv/display device is the most important item and seems to be left out of your post.The basics dictate if you have this HDMI input on your tv, that, is what you should be using.--Then you should be using a source that has HDMI-out.i.e.the cable co.'s 8300-hd cable box,as an example. When and if you go for HD-DVD or Blue Ray you must use this hdmi for 1080 resolution;otherwise it will revert to 720. The new audio for these new formats require an hdmi capable receiver--- or the 5 analog inputs from the new player.---
To recap you have audio AND video conciderations---these are mostly only important when you move to the new formats.---BTW, this is why there is so much buzz re. 1080p tvs and all the newer/better avr's have hdmi switching.
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"The hi-definition can only be sent via HDMI."

Not quite.

High def vidio can be sent via a DVI connection.
HDMI adds digital audio.
If you use DVI you need to connect analog out/in audio seperately.
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I've confused myself. Currently the cable box is HD but does not have an HDMI but a DVI connector. My Denon is HMDI as well as the HDTV. I am using AQ component from DVD to the BK AVR from and using Fiber for digital sound from TV to AVR.

How much of a difference is it between HMDI and Component. Thou I set DVD to 1080i resolution to broadcast. This this make more sense?

If you dont have a big screen then the improovement is not that dramatic, I prefer my AudioQuest Comp video cables to the DVI input.....the DVI wire is not a super high end wire tho.
I would do a high quality DVI cable with a good Coax digital cable over using HDMI.
If your cable box is older with only a DVI output and your TV has an HDMI input, you do one of two things. First, you can get a cable with a DVI connector at one end and an HDMI connector at the other end. Second, you can buy a DVI to HDMI adaptor and plug this into your cable box DVI output. Then you can run a regular HDMI cable from the adaptor to the TV.

HDMI transmits video and audio both. However, DVI is only video. Therefore, in addition to the DVI to HDMI cable connection, you also have to use separate audio cables.

It does get confusing.
Hi-Def can also be sent by component video and VGA. Some older TVs and monitors only have these inputs. And even many new ones have component as a Hi-Def option.