How do you create an image for HDTV 720p resolution? Aspect Ratio q

I'm just a bit confused about this.

720p is 1024x720. So if I create a document at that resolution, that should be it, right? But in the New Document dialog, there's a dropbox for Pixel Aspect Ratios and one of them is D1/DV NTSC Widescreen (1.2). Do I leave the aspect ratio at Square, or do I choose this Widescreen option?

* bump*

The 720p HDTV format is not 1024 X 720. The correct pixel ratio of 720p is 1280 X 720. FYI, the 1080 format is 1920 X 1080. Both HD formats use normal square pixels.

Standard NTSC and PAL television sets display non-square pixels 90% of normal width. For instance, a DVD standard 720 X 480 image will appear to occupy the same amount of space as a 640 X 480 image.

Anamorphic enhanced DVDs feature a squeeze where a normal 720 X 480 image is expanded to appear as if it were a 864 X 480 image. This is where your "NTSC Widescreen" setting comes into play.