Excel 2003 auto fill

How can you create an autofill over two columns? I use an aging report every week and on it list in column A the past due customer’s names & in column B the customer’s acct#. I’d like to be able to enter all the customer’s names & acct #’s elsewhere in the worksheet (perhaps the bottom of the page) so when I type a customer’s name at the top of the page the acct# will autofill in column B along with the completion of the autofill on column A, their name. Does anyone know who this can be done? I don’t want them to appear in the same column.