If your Windows OS keeps on giving you the alert that your XP is not genuine, you can avoid this message using following steps;
Just try this patch
Lauch Windows Task Manager.
End wgatray.exe process in Task Manager.
Restart Windows XP in Safe Mode.
Delete WgaTray.exe from c:\Windows\System32.
Delete WgaTray.exe from c:\Windows\System32\dllcache.
Lauch RegEdit.
Browse to the following location:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\Notify
Delete the folder ‘WgaLogon’ [...]