Thank you for your reply, the first part was what I was hoping to hear.
The replacement is the same model and looks exactly the same.
I suppose I would have to look at some label on both motherboards to find something like a model number?
I don't know if I have an installation disk but I will start looking, the computer must be 8 years old at least but I really like it.
I print a lot of photos and use an old Dell Trinitron CRT monitor which must be now over 10 years old.
I tried to understand colour management but couldn't so I played about with everything I could find and managed to get the printed photo to look like what I saw on the screen. I hoped that these settings whatever they were would be stored on the hard disk so that when I changed it my pictures would still look fine.
I apologise for boring you with all this and thanks again for helping
Bill Holland