See this link ... if you can see his files, it should work
When Windows XP was released everybody was complaining about the activation... As time went on people began to realize that they could backup their activation file. I get enough people asking about this that I thought I'd just put the information here. All you have to backup is two little files!
Go to your _
WINDOWS\System32\ and find a file called "wpa.dbl" and "wpa.bak" back those files up to a floppy, CD or whatever you want to put it on.
When you want to restore these files go into safe mode and put them into your windows\system32 directory. When you reboot you should be activated without actually going through MS