Got this from Tech Republic
Have you ever wanted to reformat the hard disk and reinstall Windows XP on a system but you didn't want to mess around with Microsoft's Product Activation after the reinstall? Fortunately, you don't have to.
As long as you aren't making any hardware alterations, you can back up the activation status files before you reformat the hard drive and then restore them after you reinstall the operating system.
To perform the backup, follow these steps:
1. Use Windows Explorer to open the C:\Windows\System32 folder.
2. Copy the Wpa.dbl and Wpa.bak files to a floppy disk or CD.
To perform the restore, follow these steps:
1. Decline the activation request at the end of the installation procedure, and restart Windows XP.
2. During bootup, press [F8] to access the Windows Advanced Options menu.
3. Choose the Safe Mode (SAFEBOOT_OPTION=Minimal) option.
4. Use Windows Explorer to open the C:\Windows\System32 folder.
5. If they exist, rename the new Wpa.dbl and Wpa.bak files to Wpadbl.new and Wpabak.new.
6. Copy the original Wpa.dbl and Wpa.bak files from the floppy disk or CD to the C:\Windows\System32 folder.
7. Restart the system.
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