My parents have a 1.86 17 inch iMac. It's about 4 years old. About a 1/3 of the screen is completely white and another 1/3 covered in black with red/pink, and green lines running down it. Is this the screen dying? or maybe the Graphics Card? How much would it be to repair the iMac without Applecare? Will it be cost more than the computer is worth? Is it better to just buy a new iMac. Any help is greatly appreciated.