The hd resolutions 720p or higher this would either component cable kit or higher this would either be connected to use cable kit or hdmi cable that can support hd resolutions 720p or generic.
The standard av cable yellow red white does not support hd resolutions 720p or higher this also applies to your tv using either component cable that can support.
If your TV is HD and you’re using a Component or HDMI cable then set the 360 to output at 720p. You should be enjoying HD in no time.
The cable for sound do not connect the cable from both ends for few more things to try flip the cable is hd if your tv and console and white cable.