My PowerMac G5 and 20" display are starting to feel old. It is a great machine though so I dont want to get rid of the computer. I was thinking about just upgrading my monitor and got a couple questions. I was looking over the guide... http://guides.macrumors.com/Apple_Cinema_Displays I have the first 20" model in the current form factor. Has the upgrade in Contrast Ratio and Brightness been noticeable since they bumped it up in the most recent update? What exactly is the Contrast Ratio? My main question is why the 23" and 30" say HD. What is it that makes them HD? I am plugging them into my computer... HD is really only relevant in television. Is it just because they meet the standard for being an HDTV that we call them HD Displays? Is there something I am missing here?