Comparing Excel Sheets

I need a software (Executable) that would compare excel workbooks. Important notes: 1. The workbooks come with a different design each time, they will need to be cleaned. 2. Every workbook has unknown sheets, usually more than 10. 3. Every workbook has at least 3 columns: Catalog number, Product description & price. 4. Every month we receive a new workbook that needs to be compared to the old workbook. For example, I receive the August, 2009 workbook and I need to compare it with the July, 2009 workbook. The output needs to be as follow: 1. Products taken off (Products that appeared in the last workbook but don't appear in the new). 2. Products added (Products that appear in the new workbook but don't appear in the old one). 3. Products that had a change in price. We need an executable file that would let us choose the old workbook and the new one and then compare them. The output needs to be in excel format. Thank you very much.