I receive a spreadsheet from someone outside of my company's network. I take
this spreadsheet and add columns to either side for my company's data.
Example:

Original spreadsheet ("OS")
A B C
1 pear 1354 04-Sep-07
2 lime 2000 01-Jan-08

My spreadsheet ("MS")
A B C D E
1 data pear 1354 04-Sep-07 data
2 data lime 2000 01-Jan-08 data

When the other person adds or changes their information, they send me a copy
of their updated spreadsheet. What I would like to do is use a macro to
compare the array A1:C2 ("OS") to the array B1:D2 ("MS") to find the updates.

Can anyone help me?