OK the discoloration in the corner may be due to some electro magnetic interfernece that it picked up in transit. With a screen this size it will have an automatic degausing coil and after a few times swithed on and off it may clear by itself. You know when the coil is working as it will make a bassey ping noise when the tv is switched on.
If you have sky digital then in the user menu picture settings you should set it to 16:9 wide mode and RGB out. Make sure that the scart lead runing from the sky box to the tv is pluged in to the scart on the tv that will take an rgb signal. If you dont have a scart connection and are just using an arial lead, GO GET A SCART

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I can understand that you may be a bit disapointed with the size compared to your old tv, but did you see one before you bought it?