How are you displaying your Xbox 360 - with or without an HDMI cable? We just bought a new TV today (yay! lol) and since it's HDMI capable, we bought an HDMI cable and hooked the Xbox 360 up with it. Man, does it make a WORLD of difference!
I'm planning to get a new TV soon and was wondering about the high definition issue with Xbox. It sounds like I will be in for a treat! I read something about contrast ratio being important, but I've only started looking.
When we first hooked the Xbox 360 to the TV, we didn't have an HDMI cable, and when my husband started playing Call of Duty, there was some fuzziness whenever he moved and a slight lag time between his directing the character to move and the character actually moving. When we bought the HDMI cable and started using it though, it solved both problems. With the HDMI cable, everything displays clearer, crisper and brighter than without it. I never would have believed a different cable would make such a significant difference if I hadn't actually seen it for myself!
I don't think you can get the high definition effect without the HDMI cord connecting the TV to the Xbox. Without the cable, you would still get the regular audio and video signal. If you use the red/green/blue connectors, you can get better video but not audio.