Thank you so much for your help so far. I have been trying in vain to implement the new column as you explained, but have so far been unsuccessful. I do have a little bit of a programming background and tend to be able to figure things out myself - but not this time.

instead of assigning it to the fixed array, you need to build an array with your values. If you're storing the values in a CCK field, iterate over the products and extract the value of those CCK fields then put them in the array.

I have tried to do the above - could you please explain further on the code that I need after $data['field_exterior_length'] ?

Again, thank you kindly for your time~