The Payroll version 7.9.4 or higher has the new federal tax tables as published by the IRS in February 2009 mandated by the Stimulus Package law. The tables included in this version are available to check in Publication 15-T that should have been mailed to you the middle of March 2009 by the IRS. If you did not receive this publication by mail, you can download it at irs.gov. The Payroll program uses the percentage method calculation based on the annual table.
If you would like to read more about what the IRS says about this change, please click on the following link: New 2009 Withholding Tables.