I have a 17" MacBook Pro 2.17 GHz, sometimes the screen is grainy or pixelated, and seems to flicker a little, sometimes it works perfect, For the last week it has worked perfect, today it is grainy. any idea what could be causing this and what it will take to fix it.

It is hard to say. I would first make sure you are running at the optimal resolution. Some of the smaller resolutions can cause that blurry or grainy effect.

But other than that, it is probably going to be a hardware problem. One good test to narrow it down is to tilt the display back and forth. If you see the problem get better or worse or flicker depending on the angle of the display that would lean it towards the cables getting pinched in the hinge.

If that doesn't affect anything it is probably going to be a defective LCD, but there is a slight possibility of it being the main logic board.