If you don't know where you go, get back where you come.......Hi,
Here are the steps on how you can install xp on pre installed win 7.
On the Setup of your BIOS,
Choose the ATA instead of AHCI on the SATA configuration..
then now apply the changes. then insert your cd on the cd rom. make sure you have chosen the cd as your first boot device.
Read this FAQ for more informations: