Well the problem you will have is WinXP is generally on a NTFS formatted drive which WinME won't see or recognize. Do you have a floppy drive? Download a Windows ME - Mirror bootdisk from http://www.bootdisk.com/bootdisk.htm.
Make a boot disk, make sure the boot sequence in the BIOS is set to floppy. You haven't said how big the hard drive is? If its 60GB or less run Fdisk when the floppy finishes booting and delete the current partion. With Fdisk you can check the partions and sizes you have. Then make a new partion, after a restart format the drive the WinME should bootup after you change the boot sequence back to CDROM.
Windows ME (spare computer)
Windows XP 2002 Professional SP3 (desktop computer)
Windows 7 Professional SP1 32bit (laptop computer)
Windows 8 64bit spare drive for laptop computer