you have to make sure boot order is CD. Go into bios, (F12 I think, look at the very first screen you see), and scroll around until you find boot order. First should be C drive, then cd disk. Change that so that CD is first, then C drive. Then put in your winXP cd and restart.
keep your hand on DEL button then it will go threw things then it goes to your bios when in your bios it should say advanced bios somet like tht go in there then boot first from your cd drive then your HDD twice then disaable your floppy.