Problem Solved.  The problem was in the BIOS - for this particular M/B, only HDDs show up in the advanced BIOS config pages, whereas IDE channels connected to optical drives (for some reason) are shown as a blank.  I checked this - as when the POST screen flashes up momentarily, the optical drives are shown as connected.  (The reason they do not show up in the advanced BIOS settings still baffles me.)  

ambra4 - That was the first thing I tried, but thanks for the suggestion.

Fruit Bat - thanks for the tip, I will try that next time if I come across missing optical drives in XP again. 


