HD DVD resoultion question

So I've had the HD DVD player for quite a few months now and I'm starting to notice something and I'm hoping someone can confirm this for me. I have an older HDTV and it only has 480p, 720i and 1080i. I have my 360 set to 1080i output and when I play games everything looks great. I'm noticing however when I play HD DVD's that only say 1080p on the back of the box that the picture isnt that sharp. It doesnt look bad by any means but it just doesnt look right.

Does anyone know what the 360 will do when you cant play the movie in 1080p? Does it downgrade it to 1080i or does it drop it all the way down to 480p since I dont have a 720p input?

Oh boy. First, whats the make/model of the tv? LCD's have a native resolution (if it's older, it's probably 720p). The xbox 360 will scale the image of a 1080p dvd to the output level selected in the system menu tab. So if you have selected 1080i as the output level of the xbox 360, the xbox will scale (down in this case) the video to 1080i, which may cause a little change to the over-all picture quality. Most HD-DVDs are going to be sold as 1080p because this is currently the highest resolution that HDTVs can display.

its aphillips.To be honest I'm not sure what the native resoultion is as I bought the TV used but I know its not 720p since my tv only does 720i.

I guess it comes down to how does the 360 downgrade the resoultion. If the tv doesnt do 1080p does it show it in 1080i or does it downgrade it in my case to 480p since I dont have a 720p resoultion.

The model number will be on the back somewhere on the tag. I've never heard of any television displaying 720i. Is this a tube? Or LCD? Or plasma? If your xbox 360 is set to 1080i output, the HD-DVD will scale to 1080i.