I feel your pain
I have a Denon AVR 3208 (with inputs from DriecTV HDTivo receiver and Toshiba progressive scan DVD) which drove my panny 42 for more than 5 years. You could clearly tell Hi Def from 480p, but everything looked at least ok. I recently purchase a panny TH-58PX600U and the picture is badly pixilated on every input except HD. I'm going to change setting on all inputs to 480p and let the panny upconvert, but am trying to purchase a new AV Receiver with HDMI upconverting. Started 1 1/2 months ago by ordering a Pioneer VSX84TXVI A/V receiver first from an online retailer who, after two weeks admitted that they did not have product in stock and offered to cancel order and they hadn't charged my credit card. Honest vendor. I called another online retailer who "guaranteed" that he had 20 units in stock and could ship next business day. I ordered and even succumbed to upgrading shipping and bought extended warranty. Three weeks went by and, while they offered upgraded shipping and a 3m HDMI cable, no shipment. Got my credit card bill and found they had charged my card the day I ordered so cancelled order. Bad vendor.
So, here I am, almost two months since I first ordered a a Pioneer VSX84TXVI A/V receiver and have nothing. Should I continue my efforts or should I be looking at another receiver?
Still waiting and wanting.