Hi James, I read your comment and thought you might want to try resetting the PS3's picture output settings. To do this, hold down the power button when turning the ps3 on. You should hear a series of beeps after a few seconds, the ps3 will reset and hopefully come up on your screen in a very low resolution. It will ask you something about an HDMI cable being detected and whether you want to optimise the settings for the screen - select yes. You should now have the wonderful Full HD picture back!!
Hope this helped. Enjoy your new TV - i'm very jealous, it sounds amazing!