I have a late 2006 iMac 20" that, frankly has been a bit unstable since day one. It recently got a lot worse, crashing at every opportunity, several times a day. It was also having graphic distortion / weird lines much of the time. I called Applecare, they quickly diagnosed a probable bad graphics chip/logic board. I was directed to take it to a local Apple retailer/service center. They checked it, ordered the part. The part arrived the next morning and by 2:00 I picked it up. I was told that the retail cost of the logic board and the labor were over $700! The $249 cost for extended Applecare was a bargain, huh?