These are the base optimal settings and of course the brightness/contrast can be changed and tinkered with to suit your room. (Should do it in game if you really want to alter then its custom for each game.)
Fist is the TV settings, then Ill provide the 360 settings.
Mode - Movie
Backlight - 6 (this is personal)
Contrast - 93
Brightness - 44
Sharpness - 0 (dont need it, just adds lines and jaggies that the game developer didnt put in there. Sharpness is for old CRTs)
Colour - 52
Tint - 50/50
Detailed Settings -
Black Adjust - Off
Dynamic Contrast - Off
Gamma - 0
Flesh Tone - 0
Edge Enhancement - Off
Colour Space - Custom (Continued below)
Red - 23/0/0
Green - 0/38/0
Blue - 0/0/43
Yellow - 43/43/0
Cyan - 0/46/48
Magenta - 27/0/45
White Balance -
26
25
25
13
25
15
Picture Options
Colour Tone - Warm2
Size - Just Scan
Digital NR - Off
HDMI Black Level - Normal
100hz Motion Plus - Off (Can use it on Low for racing games, but is a BIG NO NO for FPS)
Xbox Settings
Assuming you're hooked up via HDMI -
Firstly DISABLE display discovery. You will be amazed at how un-useful this feature is.
HDTV Setting - Either 720p or 1080p
Reference Levels - Expanded
HDMI Colour Space - RGB
All Done!