compare 2 worksheets with countif?

I'm trying to compare 2 different worksheets which happen to be 2 different reports in a csv file i then open up with excel.

I need to compare the 2 reports data against each other and identify the records that don't match between the two.

Can i use something simple like a countif and conditional formatting function? I've seen posts that link to sites for add-in downloads, and i'm trying to avoid purchasing an add-in.

The issue i'm having with the data is multiple records for each customer.

Example of data comparison I'm trying to achieve:
Worksheet A
Purch Date Customer Amount
10-12-07 cust1 10.00
10-12-07 cust1 9.50
10-15-07 cust1 2.25
10-11-07 cust2 1.00
11-01-07 cust3 120.00
11-10-07 cust3 82.00

Worksheet B
Purch Date Customer Amount
10-12-07 cust1 10.00
10-15-07 cust1 2.25
10-11-07 cust2 1.00
11-01-07 cust3 120.00
11-10-07 cust3 82.00
11-12-07 cust3 4.50

i would like to highlight all rows that don't match up between the two worksheets, and each customer may have multiple records on either report.

Any suggestions?