Ok here's some opinions and facts. Terrible spelling and grammer, in no order, random brain dump:

Right now you won't see much digital cable in 1080p AFAIK. And until you spend the bucks for an HD-DVD player you won't see much different in DVD from 720p to 1080p. Sure, the upconverter looks great on it, but is it worth all that extra money when you could get a game console, great audio system (upgrade whatever), games, dvds, etc. Just my opinion.

Consider your room setup, and size. Being close to a fairly big sized LCD you will see the screen door effect, it's like looking through a screen door. Plasma technology is great for it's compact size but the life span is short compared to others (lcd, tube, dlp).

Tube HD is ALWAYS the best technology, but is heavy, if you don't plan on moving, a great option.

I personally have a samsung DLP 720p. I have seen the 'rainbow effect' people talk about only once in my whole year of viewing. You have to replace the bulb which is exactly like changing a household light bulb (on the samsung anyway). DLP form factor is much smaller than regular rear projection and can sit on a tv stand. If the mirror (dlp tech) is messed up, replace it. A big pro over LCD and plasma, where if you've got a couple dead pixels you're pretty much out of fortunateness (luck :p)

I notice that when you look for HD, you end up looking close at every single artifact on screen, instead of enjoying the HD in general. For example, I notice the slight sheen of my screen on vibrant whites, but I notice it only when I'm being way to critical.