|If you just want to REFORMAT without installing windows XP, you can use FDISK from Win98/WinME Boot Diskette provided you have a Floppy Disk Drive.|
If you don't hava a FDD, you must first create a Bootable FDisk CD in a CD burner with a Burning software like Ahead Nero/Roxio ECCD Creator and then use it to Format the HDD.
If you want to Reinstall the same OS and software from Toshiba, contact them with your PC specs, Serial #s etc and get Recovery Disc.
If you are using a Genuine Bootable WinXP CD, you may still have to get Drivers for the Hardware from Toshiba; check the feasibilty for that before formatting the Notebook HDD.
Since you did not say why you wanted this specific "treatment" (Reformat) without giving us a clue about the symptom , no other alternatives can be offered at this time:-)
Good luck whatever you want to do.