It wasn't the screen size, Craig. The screen image was a small window on the computer screen, comparable to the DVD player. The problem I've been narrowing it down to is the video grabber that's converting the signal from the camera to a format that the computer can read. "Lost in translation" comes to mind...
There are also a few more settings I can play with on the camera. See how I go. But the image quality I'm getting on a dedicated monitor is just what I'm after. I don't do many screen grabs, and I don't capture video for post-processing work, so the camera-straight-to-monitor rig is good for me,
But it is a good idea to improve my on-computer image too.