How to remove Windows XP Professional x64 Edition from a computer that is also running a 32-bit edition of Windows XP

After you install Windows XP Professional x64 Edition on a computer that is running a 32-bit edition of Windows XP, you may want to remove Windows XP Professional x64 Edition and continue to run the 32-bit edition of Windows XP. This article describes how to remove Microsoft Windows XP Professional x64 Edition from a computer that is also running a 32-bit Edition of Microsoft Windows XP.

Note This article applies only to a situation where you have installed Windows XP Professional x64 Edition on a separate partition from the 32-bit edition of Windows XP.

Because Windows XP Professional x64 Edition is a stand-alone version of Windows, you must remove the associated entries from the Boot.ini file. You must also remove the operating system files from the partition on which Windows XP Professional x64 Edition is installed.

Important Before you format the partition on which Windows XP Professional x64 Edition is installed, you must back up all the data from that partition. Formatting removes all the files from the partition. If you have other information about this partition, do not format it until you have performed a full backup.

Step 1: Remove the entries from the Boot.ini file

1. Start the computer to the 32-bit version of Windows XP.
2. Log on to Windows XP by using an account that has Administrator rights.
3. Click Start, click Run, type c:\, and then click OK.
4. On the Tools menu, click Folder Options.
5. In the Folder Options dialog box that appears, click the View tab.
6. Click Show hidden files and folders if this option is not already selected.
7. Click to clear the Hide extensions for known file types check box if this check box is selected, and then click OK.
8. In the Local Disk (C:) dialog box, right-click Boot.ini, and then click Open.
   
   The Boot.ini file opens in Notepad. The contents of this file appears similar to the following:

   [boot loader]
   timeout=30
   default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
   [operating systems]
   multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect /NoExecute=OptIn
   multi(0)disk(0)rdisk(0)partition(2)\Windows="Microsoft Windows x64 " /fastdetect
   C:\="Microsoft Windows"

9. Remove the following entry from the Boot.ini file:

   multi(0)disk(0)rdisk(0)partition(2)\Windows="Microsoft Windows x64 " /fastdetect

10. Modify the Advanced RISC Computing (ARC) path next to the default entry so that this path points to the location of the 32-bit version of Windows XP. For example, make sure that the default entry appears similar to the following:

    default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS

    Note If the default entry points to the ARC path of Windows XP Professional x64 Edition installation, and if you remove the entry for the Windows XP Professional x64 Edition installation, you will receive an error message when you restart the computer.
11. On the File menu, click Save.
12. Quit Notepad.

Step 2: Remove the Windows XP Professional x64 Edition files

To remove the Windows XP Professional x64 files, you can remove the Windows folder by using Windows Explorer, or you can format the partition on which Windows XP Professional x64 is installed. We recommend that you back up the data from this partition before you follow these steps.

Remove the Windows folder

1. Click Start, click Run, type Explorer, and then click OK.
2. Locate the drive that contains the Windows XP Professional x64 operating system files.
3. Right-click the folder that contains the Windows XP Professional x64 operating system files, and then click Delete.
   
   Note Typically, Windows XP Professional x64 operating system files are located in a folder that is named Windows.
4. Click Yes when you are prompted to confirm the removal of this folder.
   

Format the partition that contains the Windows XP Professional x64 Edition files

1. Click Start, click Run, type compmgmt.msc, and then click OK.
2. Expand Storage, and then click Disk Management.
3. In the lower right pane, right-click the partition that contains the Windows XP Professional x64 Edition operating system files, click Format, and then click OK.
   
   Important Do not format this partition if this partition is the system drive. The system drive contains the following startup files that Windows requires:
   • Ntldr
   • Ntdetect.com
   • Boot.ini
   If you format the system drive, you can no longer start Windows.

For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base: