The video iPod has a 320x240 display. Consider that in your choice.
Crisp and clear digital 320x240 should equal a staticy 640x480 analog. A fly in the ointment maybe dark scenes, which frankly makes up a lot of BSG - either the H.264 algorithm isn't good at it, or the person overseeing encoding must do a better job on the examples I've seen.
The thing that I've noticed is that while picture quality is nice and isn't unimportant, the story is more the thing with TV shows.
I know I'm not the only one who is hanging onto cable just for a show or two, and maybe enough of us dropping will force them to upgrade picture quality AND drop rates and/or switch to an ala-carte program plan.