You don't need a big screen to see a difference. Even on a 19" screen its like night and day. If you have a good monitor and good source that is--when most people say "theres not that big a difference", they have seen 720p examples of some crappy HD television broadcast compressed to death on a crummy TV to begin with. If you can't spot Blu Ray on a 19" 1080p television I would say you might need to get your eyes checked.

NTSC and PAL aren't obsolete yet, because standard def is not obsolete. Not only is standard def not obsolete but its by a huge margin the majority format. One day it might be though, but not for a while. LCD's and digital signals don't make a difference.