hey guys, Have you updated your copy of Windows and received the "This copy of Windows is not genuine" notification. Now Obviously You want to get rid of it.. First Take A Look what the Real problem is. The Windows Genuine Authentication notification checks whether you have a genuine copy of Windows registered for the computer or Not. It permits you to update your computer with the Windows updates. If you have installed it, and you do not have a genuine copy of Windows XP installed (which is Obvious in your case :P), then you may notice an icon at the bottom of your window before you Login. It will make you wait three seconds before allowing you to login. And Keep Remain on your Desktop and Also can stop your Wallpapers on Desktop.
Restart your computer and boot into safe mode (press F8 while you restart your computer)
In Safe mode go to C:\Windows\System32\
Search for WgaTray.exe and Delete it.
Now go to C:\Windows\System32\dllcache\ and delete WgaTray.exe here also
Here The Windows Registry is Also Gets Affected by WGA..So We have to Fix it Too..
Click-> Start Button > Run and type regedit and then press enter.
Go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify and delete the WGALOGON folder.
That's it you're done. Now reboot your PC and enjoy the windows but don't forget to disable your updates this time.