Hmm, if you tried the PS3 via HDMI and everything works fine, then it doesn't sound like the scaller. It my just be an issue with the analog inputs (component/VGA). The red issue sounds like the analog board since you ruled out the 360/cable.

You don't "need" your component inputs if you don't have any older devices that only have conponent outputs and you have plenty of HDMI inputs (at least 3).. But it is a new TV that is under exchange, so why not make sure that EVERYTHING is working properly. I know it is a hassle but worth it in the long run IMO..