A 1080i source in a 1080p HDTV can be deinterlaced to produce a progressive image.
A good scaler like the DVDO VP20, 30, 50 can properly deinterlace or upscale all sources to 1080p.
So instead of buying an awefully expensive 1080p SD-DVD player,standard DVD players with upscaling up to
1080i, (Pioneer's DV989i) can be deinterlaced to 1080p with the help of an internal scaler of a 1080p HDTV, receiver, or scaler like the DVDO.
There are only so much SD-DVD players which can upscale to
1080p. Some of the known brands are Denon (A1XV(A) has an internal DVDO scaler

), Marantz (DV9600) , Arcam , and NeoDigit Helios.
The best 720p or
1080i upscaling SD-DVD like Pioneer's DV989i and Yamaha's DVD-S2500 offer tremendous performance for half the price of 1080p SD-DVD players. Unfortunately,only if u have a 1080p HDTV.
Many 1080p HDTVs deinterlace 1080i to its progressive format, 1080p. Although most 1080p TVs sold currently does'nt accept a direct 1080p input, they deinterlace 1080i inputs.
Most HDTVs that accept 1080p24 inputs (1080p 24 HTz,Blu-ray and HD-DVD) like Sony's VPL VW50 front projector, plays the video at 96 fps. 1080i could also be fed, deinterlaced to 1080p, and then viewed at 1080p60.
1080i is more or less half the resolution of 1080p.
Yeah your right, we'll need a 1080p display to truly show 1080i, but if u have a 720p native HDTV, feeding 1080i to eat gives a
soft film like picture and not sharp enough (for my eyes at least

) , since it then shows the image at its native resolution loosing some pixels (115200 of them if your TVs resolution is 1280 x 720 ). So,to me I personally like to feed a TV with a resolution of it's panel, as it gives a sharper look to me.
Well, I'm off now to go to mediaplex and Demo Sony's Ruby. Toodledoo!!