I have a Polaroid PDM-0711 Portable one. It has a 7" Screen (you really don't want to go lower than that) and what I like about it is that it's very good with dark scenes.
From what I have heard, some Portables are washed out looking during any scene in a given video that is dark (like if someone is walking down a dim lit hallway), but the Polaroid I have is great with that.
Also, just on a side note, I wanted to tell everyone something in here that really impressed me about it. I bought it for Christmas of 2005 (last year), and when I got it I was using it mostly with the A/C Power adapter. Then I charged the battery and disconnected it and put the battery in the box it came in and stored it in the attic (because I wasn't using it for a while). Recently, back in November (this year, 2006) I lost power in my house for several hours. I went in the attic, got the battery for the Portable, attached it (fully expecting it to be dead as I charged it a year ago) and it worked long enough to watch a whole movie on.
I didn't even run it until it died, so it might very well STILL have juice in it.
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