Excel 2007 : arranging/sorting multiple lists

Here is the scenario:

I have two sales reports. One is total sales per customer for 2009-2010 and the other is total sales per customer for 2010-2011. I want to be able to see the difference in sales per customer for each time period.

Ideally, I would like to arrange my information so that a customer's 2009-2010 sales are in one column and their 2010-2011 sales are in the next. The problem that I am facing is that there are thousands of customers and some have not made purchases in both time periods. Therefore, both lists do not have the same amount of rows.

Without going through the list one-by-one and inserting and deleting rows, is there a way where I can make Excel group the same customers together side-by-side?

Any and all help is greatly appreciated. Thank you.

A pivot table will work perfectly for this. If you have some sample data and are unfamiliar wiht pivot tables, post a file up and I will create the table for you.