Video boards also fail, although you're more likely to get screen flicker.
A good news story. My 3.5 year old 17 inch MBP video screen died (screen just turned black). I took it into an Apple store, it was out of warranty, and they quoted $2,200 to replace the video board BUT fixed it for FREE. And they did it in 3 days over a long weekend.
This is my second video failure and it is related to the fact that I also use a 32" cinema screen plugged into the aux video port.
Amazing service!! Thanks Apple.