All had apparently gone but no resolution fix. Restarting I got my desktop nVidia chipset update icon back and installed that OK (this fixes the resolution until I restart then it's back to 640x480). Then I found I could not connect to the internet and found in the Device Driver list that the SM Bus Controller and the Other PCI Bridge Device had the yellow question marks attached.
Windows kept on saying that it had found a new hardware wizard and asked for a CD containing the the needful (I only have the XP Pro installation CD which doesn't help) or to look on the internet for it but as now I cannot connect to the internet I am stymied.
Does the lack of these two components mean that internet connection is impossible?
Can I download a fix on a memory stick on another computer to transfer?
Any enlightenment on this dilemma gratefully received.
(I've looked at the relevant forum posts on Bus Controller problems but can find no equivalent problem)