yeah so i dont have a HDTV monitor, in fact, my TV is so old school it doesn't even do 480p. it's a standard def Sharp 3:4 32" CRT.
it does, however, have component inputs so that's what i've been using with the HD component cable that came with the 360 (setting the little switch to 'standard defnition').
this is apparently not advisable according to the cable manual. apparently they want you to use the composite connector for the standard def. TV.
and according my recent help chat over the xbox website, she claims a S-video connector would actually generate a better picture quality on my standard def. TV (better than the component outputs? wtf?)