Here's a tip for future TV shopping: If your TV is pretty inexpensive, don't waste 20-40% of the purchase price on an extended warranty. In the event your TV fails, you'll get a new set for not much more than the entire extended warranty cost.
Some credit cards will give 2x the mfrs. warranty if you use them, as will Costco. Consider those outlets before shelling out $300 for a warranty on a $900 item that will be $500 in 3 years to replace.
There is no difference in HDMI cables. If you can see the picture without visible dropouts or sparklies, the cable is working at 100%. No other cable will display a better version of that picture. You're simply wrong if you think there is a better digital cable than one that is already working.