Originally Posted by evilchris
720p is 1280x720. Even average joe who is blind can see a massive difference between HDTV and SDTV.
Yeah, but 1280x720 is 16:9, while 640x480 is 4:3. That's why I mentioned pixel density, as you want to compare apples to apples, which means pixels/square inch. That means you have to compare resolutions at the same aspect ratio.
For such comparision to be meaningful, you have to compare either 640x480 to 960x720 (for 4:3), or 852x480 to 1280x720 (for 16:9). Those are the relative differences between the resolutions in question, and if you want to try a Pepsi challenge, those are the resolutions you'd compare on, for example, a vga monitor. Same goes for the jump from EDTV to HDTV. The difference is noticable, but not revolutionary, and nowhere near enough to spoil the enjoyment of the experience.
The point is that the difference in quality most people attribute to the jump from standard-def to hi-def has much less to do with the actual resolution than the move from a composite cable to an RGB (component) cable.