I have 2 files that contain sales information for our customers for 2003 and 2004. In each file i have created a layout with summary fields that sort the sales so that we can see how much in sales each customer has purchased per manufacturer. I would like to compare the summary information in each file (comparing 2003 to 2004), but am not sure where to start. Is this possible?

Assuming you're using version 6 or lower, you can create a calculation field of CustomerID & " " & ManufacturerID in both files. Then create a relationship in the file where you want to display the info (or in both files, if you prefer) based on this calculation field. Then you can create a calculation of Sum(relationship::Amount) and put this field on your layout to calculate the total related Amounts per client per manufacturer.