XP won't boot to CD

[TurboMike]

Got a PC with XP from a auction that has XP but I don't have a password to log on. So i want to install my OP (windows2000 Pro). I went into setup and changed the boot sequence to first boot CD, put in my 2000 pro and it still boots to XP. Any one know how I can get it to boot from the 2000 pro cd so I can format the HD and install 2000?

 

[TurboMike]

booted with win98 to a: then fdisk. It says no space to create a partition and no partition to delete!