I thought we went over this, but I'll try again.
Upconverting comes in several flavors and one of the best flavors is pixel for pixel mapping.
Take a display that has a native resolution of 1365x768 pixels (WXGA). That display must covert any image put on screen to 1365x768 before you can see it. Since no broadcast standard includes 1365x768, this means that you are sending it something different, and it must be up converted, or down converted to 1365x768 progressive. This is the law with all 1365x768 fixed pixel displays. There are a very few that will allow 720p to actually only use 1280x720 pixels, but these are few and far between.
The actual term for what is going on is scan converting. Taking a multitude of different format inputs, and converting them into one specific output. This already happens inside your plasma, lcd, dlp, lcos device.
Once you understand that a computer chip and electronics makes all this happen, and it must deal with tens of millions of pixels every second, it is easy to understand how a high quality outboard scan converted can do a much better job than the one Panasonic included for you inside their plasma.
In much the same way better audio components throughout your room can improve the quality if your listening experience, scan converters can improve the quality of your viewing experience by increasing the quality of video that is displayed on your tv.
Also like the audio section, spending the extra cash on a new product may not really give you the satisfaction you were hoping for. You may get one and only see marginal if any improvement at all. The fixed pixel display device you have may already have killer scan converters inside of it to make the image look about as good as it can. I must say, this is typically not the case and usually you will see some level of improvement between an outboard scan converter and the one inside your display.
Check
www.dvdo.com and look at their product, which I imagine you have already. You can see that their iScan HD+ product allows for full color correction, sharpness levels, and all sorts of other features that allow you to fully tweak the image before it leaves their box and goes to your display. This means that the burden of all the video processing is removed from your plasma, and now is handled inside a good outboard video processing box.
The best comparison would be buying a good A/V receiver like a RX-V2500 and then still using outboard amplifiers because it cleans up the sound and gives you more power. It may only be a marginal improvement, but it is still an improvement.
