ALL DATA ON THE SYSTEM WILL BE LOST
i like to tell people this ahead of time since some do not know this.
when starting your computer, start tapping f2 (or del or whatever the computer tells you to press to enter system setup).
once there, find the option for the boot sequence and make sure that the cdrom is selected as the first device.
insert the windows xp cd, then restarty the system
it will probably prompt you at some time to press any key to boot to cd. as soon as you see this, press the spacebar as it only gives you roughly 3 seconds
then, after setup is finished initializing and it gives you options, press enter to install a fresh copy of windows
f8 to agree to EULA.
then, press esc to continue installing windows.
when at the partition screen, highlight any partition listed other then 'unpartitioned space' and press D
then press enter
then press l
repeat that for each partition listed
once finished with that, highlight unpartitioned space, press enter
next screen should ask you what file system to use, personally i perfer NTFS and nothing else. i don't personally care for the NTFS (quick) or fat. but that's up to you
then it should start formating. the rest is self explanitory