Do I have to go to payroll office to complete Form W-9 when becoming resident alien?



I became resident alien on 01/01/2008, but the payroll office said there's

no need for me to fill out Form W-9 because I changed my visa from F2 to F1.

Is that correct?
 l know all my friends(f1 visa) signed W9 when they became resident alien.

thanks