I know this is an old thread...but I too have (had) the same problem with my Late '06 C2D 17" iMac. I didn't start having problems with it until about a month ago. I had several lines on my screen and after reading all the post here I didn't even bother to call Apple and waste my time only to be disappointed.
Rather than ditching a machine that still works perfect other than the vertical lines, I decided to do a little research. I wanted to make sure that I wasn't having a graphics card or logic board issue. So I took a screen shot of my desktop and emailed the picture to my iPhone. After looking at the picture I notice there was no colorful lines at all. I knew then it was my LCD that was bad and not the graphics card or logic board. Again, rather than ditching my machine, I decided to go to my local Micro Center and I purchased myself a nice 24" LCD monitor on sale for $79 bucks...connected it to my iMac and now I have a nice (bigger) beautiful monitor with absolutely no colors. I know this may seem like a hassle to some but I wasn't about to throw away my machine that I spent my hard earned money for when alls I have to do was add an external display and solve my issue without having to deal with Apple. Besides, in 2013 a 17" monitor is too small anyway.
Just a suggestion to anyone out there who doesn't want to throw away a good machine for a LCD problem that Apple was very much aware of...
HI, I've decided I"ll just have to bite the bullet and buy a new iMac
In this past month or so the vertical lines have started multiplying faster than in the past few years! I now have approx. 22 and they are encroaching from the left side towards the middle of the screen.
Apple told me years ago that my iMac was vintage and therefore not repairable. I have gone on using it and still can perfectly well, its just the display, but it is now seriously annoying me!
Am I mad to want another iMac? maybe but that is the way we are!!
Lets hope they never have this issue again. If the new model produces even the faintest vertical line on the screen I'll be down to their store immediately!!
I wonder how everyone else coped and whether you are all finding the same as me, after all our problem is the same and has been around for the same amount of time..