I have a 102" screen, 10 feet away...and yes, 1080p does make a huge, huge difference in resolution and detail.
Just for giggles though, I have tried 480i, 480p, 720p, 1080i as well. 720p is still pretty good looking, and far better than 480p. The jump to 1080p is at least that much improvement again.
480i can be painful now...especially if it's a compressed signal or bad recording to begin with...
Is it just me or do most of your posts start with those words now