If your os keeps on giving you the alert that ur xp is not genuine, you know that it is not but how will you avoid it.

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’ and all its contents
Reboot Windows XP
If it still dont resovle then I will suggest you to reinstall XP and when installing ,any later time, online updates untick the Geniun XP patch or what ever like this.