Cinemaddiction

I know that this sounds incredibly noobish, but after 48 hours of fine tuning my new HDTV, my mind is mush. I own a Sony DVPNS75H w/ Upconversion via HDMI. On the Setup screen, it asks whether I want to display in either YcBcR or RGB(HDMI). I took the HDMI in parenthesis to mean RGB is the same as selecting HDMI, which is what's running directly into the TV from the DVD player. Initially, it was set to YcBcR, which I don't have AT ALL, and it must have been a default setting. Should I switch over to RGB(HDMI), or leave it as is? If I were to change it, would I leave it at the TV's native resolution of 720p, or would I see an improvement having selected HDMI and 1080i for the display?

Hopefully this made sense, and thanks in advance for any advice. Just be kind..I'm new to this, lol.