Strange display patterns, any suggestions?

Hi - I have the above iMac (early 2008 20" iMac. Everything was working fine and then the screen sort of flashed and now I have these weird bands from the top to bottom - there are 13 of these bands. They appear to almost 'move' - items behind them are all pixilated. I do have a video and pics of the screen that I could send but cannot figure out a way to attach something like that to the note.

Also - if I boot it gets as far as the apple screen and they stays white. Where the pointer is, or would be, there is a pixel block. TO get it to go all the way through the boot process I booted it in Safe Mode, then it worked and I get to my normal screen but the 13 bands are there.

Any thoughts?