1. Recovery Partion or Recovery CD. Perhaps you have another option.
You say the computer came preinstalled with Windows XP Home, but no XP CD. Computers sold in this state usually come with a "Recovery CD" or a "Recovery Partition". Have you looked at the partition structure of the hard drive to see if there is a "hidden" recovery partition on it.
http://en.wikipedia.org/wiki/Recovery_partition http://en.wikipedia.org/wiki/Recovery_CDYou may use the "Disk Management" snap-in that comes with Windows XP to do this. If present, the recovery partition is usually the first partition on Disk 0. (Not sure if you need "administrator" permissions to do this. If Windows XP Home, you might have to access from Safe Mode.)
http://www.theeldergeek.com/disk_management.htm http://safari.oreilly.com/059600897X/windowsxptmm2-CHP-15-SECT-5 http://www.mcse.ms/message507297.html2. Original Configuration. What is the make and model number of the original computer that came preinstalled with Windows XP Home? Is it an OEM installation?
Does the original preinstalled Windows XP Home installation have a product key? If so, record it and keep it in a safe place.
3. What does the label say on the XP CD that you do have? Is it retail version of Windows XP Installation CD (Home Edition or Professional? Original, Service Pack 1 (SP1), or SP2?); or is it an OEM Windows XP Installation CD?