Excel 2000

I have two files, one master and one created by opening a text file. The
master file has a list of unique product codes and descriptions in two
columns, the text that is opened has the product codes and I add during the
opening process a look up to the product code to return the product
description, this all works fine. The text file after opening is 7 columns,
product code, product description and 5 columns of numbers.

What I need to do is format the cells (numbers) in the last 5 columns of the
newly opened text file. My thoughts are to add a third column to the master
file whereby I'll have 3 columns: product code, product description and
number format, in the number format column I would format the cell with the
required number format. My issue is, how using VBA do I format the cells in
the newly opened text file where the product code matches that of the
corresponding product code in the master file. The text file can have many
of the same product codes and in some instances, not all of the product
codes.

I had also thought of Conditioning Format but alas, this doesn't cover
number formatting.

Any pointers, snippets of code most welcome.

Thanks, Rob