Using a HDMI cable on an old xbox 360 model?

basically in the very new future (a couple of days) i am going to be buying, my first, HDTV and it is going to be 1080p, now i wanted to know if it is possible to use a HDMI cable with the original 20gb 360 model? Also if you can't is it going to make a big difference to my picture quality?

cheers guys and merry xmas (or when in the states "happy holidays")

If your Xbox 360 doesn't have an HDMI port, then you can't use the cable. There's little difference between an HDMI and component connection

You can buy a 3rd party adapter I think, but it will still only by 720p.

But since such an adapter will be taking an analog connection and converting it to a digital one, you're still hampered by the analog limitations (hence the 720p) and won't see any benefit. The only reason to use such an adapter would be if you had no component inputs available. Otherwise it's better to just use the component cables.

I used component when I had that 360 unit - it will give you a great picture.