is there any notablediffrence if i use hdmi cables instead of the av hd cables on a 1080i/720p tv or should i not waste my money

it didnt work this morning then tried 5 mins ago and works fine, maybe it was a temp problem for my xbox but all is good now

is any one else having problems with there xbox not letting them play there ipod any more. it shows all the songs locked now. really pissed me off