Just a quick guide for those that don’t know the know.
480i (525i) – 480 visible scanlines interlaced…NTSC.
576i (625i) – 576 visible scanlines interlaced…PAL.
480p (525p) – 480 visible scanlines.
576p (625p) – 576 visible scanlines.

Interlaced pretty much means that only half the lines are updated each update.

HD is 720p or 1080i. Anything else is not HD.

When you are buying an HD TV you need to know what it’s native resolution is. Native means what it has internally in its chip that will be pumped out to your screen. Many TVs say they support HD but internally they don’t do HD and simply resample the output when it’s actually pumped out.