Clean install on laptop...pls help.

Please help....Have just enough computer know how to get in trouble. Have a Sony Vaio PCG-GRZ530 laptop. Bought from a student at local university. Computer works just fine but doesn't have a valid Microsoft OS. Prev owner loaded XP Pro, should have XP Home. After talking w/Sony support, was told needed to clean install OS system back to original & use my XP key on bottom of laptop to get Microsoft updates, & update BIOS & other components not updated specifically by Windows, basically to have laptop run right & Sony could do all this remotely. I have the 3 application restore cd's from Sony, upgrade XP Home cd, etc. Sony said they or another professional needed to do clean install b/c drivers had to be installed a certain way, order, etc. Can anyone tell me how to do this? I have an EZ OS install cd & know how to set laptop to boot from cd & xtra backup of drivers on cd. I have used EZ OS install on my desktop before w/out any problems. Any help would be greatly appreciated. Thanks in advance. =-)