When I view my photographs through the Windows Media Center software, I especially enjoy the built-in pan and zoom effect. But if my images are shot in 1600×1200 size they are not in the HDTV format. While still good pictures, many cameras shoot in 4×3 aspect ratio.
For example (4×3 aspect ratio) 4 divided by 3 = 1.3333 and 1600 divided by 1200 = 1.3333
Try and see if your camera shoots in 16×9 aspect ratio. My Canon A710 actually has a mode that says "Widescreen" and is 3072×1728. This is correct for HDTV.
For example (16×9 aspect ratio) 16 divided by 9 = 1.7777 and 3072 divided by 1728 = 1.7777
So look for a size that divides into 1.7777 and you’ll know it’s 16×9 or HDTV. FYI 1080p and 1080i are both 1920×1080 which divides into 1.7777