K, I looked over the SD footage on my 58" Panny plasma.
On regular SD channels, they look ok, not the greatest since this is SD afterall.
Channels that are meant to be in HD but down converted to SD signals have a better picture. One movie channel almost seemed DVD like.
I have a FTA receiver (Coolsat 5000) hooked up with component cable going straight to the plasma.
I have yet to see HD footage on my plasma which I will be getting soon.
The Wii, even without component cable, looks really good IMO (despite the resolution).