TOSHIBA SATELLITE L45 S7423 LAPTOP. I AM HAVING TOSHIBA SATELLITE L45 S7423 LAPTOP WITH VISTA . I

Question

I AM HAVING TOSHIBA SATELLITE L45 S7423 LAPTOP WITH VISTA . I WANT TO INSTAL XP IN IT.
I TRYED BUT I AM GETTING THE ERROR
THAT IS "SETUP DID NOT FIND ANY HDD IN THIS COMPUTER". I TRIED THIS IN OTHER WAYS ALSO THAT IS ,

1. I COULD NOT CHANGE THE RAID MODE TO IDE MODE IN BIOS.
2. I COULD NOT CHANGE / DISABLE THE SATA DRIVER IN BIOS

I AM NOT HAVING ANY FLOOPY DRIVER IN ADDITION TO IT.PLEASE ANSWER MY PROBLEM..................IN MY EMAIL ID [e-mail]