Older iMacs with bad screens

[adam9c1]

Hi.
I have an older iMac 17 inch I think with 2GB ram running SL.
The screen has lots of small vertical lines (I have external larger monitor connected). Is this an issue with the LCD panel itself or graphics card or....

 

[iMacC2D]

Removed.

 

[adam9c1]

Aha.

Will the machine continue to run ok?
I'm considering another unit to set as offsite backup.