what is the diff. in 1080i and 1080p?

i means INTERLACED and p is for PROGRESSIVE. Progressive is a way of electron scanning the screen that scans each line (vertically) one after the other, Interlaced is a technique that involves skipping every other line on the first scan, and scanning the skipped lines on the second scan pass. Progressive has a smoother look, especially when watching sports or other fast moving video. While 120 hz scan rate is twice the standard rate and gives a great sports watching experience, response time (how fast it responds to a signal change) is just important (my LCD is 3ms response time, and 3000 to one contrast ratio). Interlaced will look choppy compaired to Progressive. Old fashioned Analogue TV is Interlaced, and the newer Digital TV is Progressive.

Plasma is said by some to have more vivid colors, but it puts off more heat and will probabally have a shorter life. It also consumes more electricity than an LCD. Once you decide on type, scan, and size, do not neglect the inputs. many of the cheaper ones only have 1 HDMI (or none!), and may not let you plug in other things like a DVD or CD Player, necessitating a Receiver (with HDMI Loop-Thru capabilities) to be in the circuit between the cable/satellite box and the TV.

My LCD has HDMI, DVI-Interface, Component,, Coaxial, S-Video(it Up-Converts older sources), as well as Digital Audio out.

In terms of actual picture quality, there's little difference. The 1080p scans all the lines at once and the 1080i scans every other line. It does this fast so your eye can't tell but progressive scanning is flicker free.

I prefer plasma. The contrast ratios are much better than LCD (lcd is getting better but still not near that of plasma). LCD motion lag really bothers me. That's the jaggy picture you get when there is fast motion in the picture. If you decide on LCD, get one with a 120hz refresh rate and fast response time to help with this. One thing about plasma's, you really shouldn't play video games on them. They are getting better but still can burn in static images on the screen. Some manufacturers have a "game" mode but they still don't warranty the tv for "image retention".

See it here:

http://en.wikipedia.org/wiki/Progressive_scan