Trouble deleting a partition

[Eg37se]

I'm trying to install Windows XP on someones computer who has Windows ME, which is terrible to begin with but made worse by the millions of viruses on there from his porn obsession. I'm having trouble deleting the partition and creating a new one, when I try to delete it, it tells me it cannot be deleted because files used for teh XP setup are being used on the hdrive. Also it will not boot the Windows XP disk. He has a Dimension 8100 and I'm really out of ideas. Could someone help me?

 

[BASSMASTER]

Download a Windows 9x bootdisk from www.bootdisk.com
run FDISK

 

[KSoD]

Go into the BIOs and set it to run Boot from CD before the HDD> By default Dell has the HDD run first then other devices. Check the BIOS to make sure it has CD before the HDD.