I've got an Archos 605, Mogui. It's great for video and photographs (which is what it was designed for), but the screen is only the same size as, say, a Pocket PC, and the latter is both smaller and lighter. Not a good choice as a book reader IMHO, but great
for video - you can record directly onto it from any video source, and it'll play all the standard video file formats.
I suppose it might be interesting, though, to read your eBook on your 40" plasma TV, which the Archos will certainly allow you to do