Excel 2000 Spreadsheet Comparison

Do you have a utility that will compare each row in two spreadsheets and output a third spredsheet of the rows? The output options are: 1. The contents of first spreadsheet is copied to the third spreadsheet cell by cell in each row so that the cells that are differences are highlighted in a preset color. 2. The contents of second spreadsheet is copied to the third spreadsheet cell by cell in 1 & 2 except that only the rows with cells that are different will be highlighted in a preset color& output into the third spreadhseet. The input spreadsheets are more than 20k to 40k rows with 10 to 30 columns in length. Some spreadsheets are 10 times more rows. I do not have any options to receive this data in another format. The Vendor only outputs Excel xls format. The end user must attempt to validate the accuracy of the data by reviewing every line/ros.