When installing Windows XP, why does Setup prompt me for a previous version of Windows?

In 2009, Microsoft began shipping Windows XP with Service Pack 3 as "Upgrade Only" media. If you have purchased this software from the Indiana University campus bookstores, note the following:

• As the Upgrade Only Windows XP media does not recognize an installed version of Windows Vista as a qualified operating system, you cannot perform downgrades from Vista to XP.
  
  
• If you try to install the Windows XP Upgrade Only media onto a partition that has been formatted, a partition that has never had Windows installed, or on a new hard drive, the upgrade will fail.
  
  
• The Windows XP Upgrade Only media will not work for Mac users, as it will not recognize a previous version of Windows via Boot Camp or other Windows virtualization software.
  
  
• The Windows XP Upgrade Only media will not work on computers that have had their hard drives replaced.

If Windows does not recognize your current operating system as a valid starting point from which to upgrade using this product, it will display an error message beginning as follows:

"Setup cannot find a previous version of Windows installed on your computer. To continue, Setup needs to verify that you qualify to use this upgrade product."

You will then need to insert a CD with one of the following operating systems, which qualify for the upgrade:

• Windows XP Home Edition (full version)
• Windows XP Professional (full version)
• Windows 2000 Professional
• Windows Me
• Windows 98
• Windows NT Workstation 4.0
• Windows 95
• Windows NT Workstation 3.51

Comments/Questions/Corrections