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"Windows Product Activation (in Windows XP) is turning out to be less of a problem than most of us had anticipated. Sure, there are a few people who can afford to make six hardware changes within 120 days, but most of us stick with (or add on to) what we already have. A question has arisen regarding what happens when you have to reinstall the new OS on the same machine. Do you have to reactivate it? Yes. Maybe. When you run all the way through the WPA wizard, a WPA.DBL file is created in your "System32" directory. Copy this file to another folder for safe keeping. Now, whenever you reinstall Windows XP on the same machine, you should be able to avoid the WPA process by copying WPA.DBL back to the "System32" directory. While I haven't run through this process myself, it should work as long as you haven't changed the machine drastically since the WPA.DBL was created. Just make sure you're using the "latest" copy of that file, otherwise you may find yourself on the phone with Microsoft. Who, according to them, will give you the benefit of the doubt every time. "