I just went out and bought a video card. "GeForce 6200" 128MB.
If this doesn't work, I quit but at least I'll have upgraded from the old harvest gold model. So now my computer won't match the fridge & cooker.
I'll be signing off shortly to give it ago but will hang around for the next ten minutes in case any of yous want to help.
Apparently there's a wee cog in there that might not fit.