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.
Browse to the following location:
Delete the folder 'WgaLogon' and all its contents
Reboot Windows XP.
Note: With this method, you may be prompted to install WGA Notifications again which can still be unselected.
1-Launch Task manager
2-End process WGAtray.exe
3-Quickly restart in safe mode.
4-Click start, then Run. Type regedit and click ok.
6-Click Software, microsoft, windowsNT, currentversion, winlogon, notify.
7-On the right hand side find folder WGAlogon and delete it and all of its components.
8-Restart in normal mode.
9-Go to c:\windows\system32 and delete WGAtray.exe file.
10-Next to it should be WGAlogon.dll, delete this too.
11-Delete from recycling bin and reboot.
This should have solved the problem but i advise switching your automatic updates to
"Notify me but dont automatically download or install them". This should
advise you if your computer tries to download WGA again.
For windows XP SP3 users try this method
1 Lauch RegEdit.
2 Browse to the following location:
3 Delete the folder 'WgaLogon' and all its contents
4 Reboot Windows XP.
Disabling and renaming the files 'WgaLogon.dll' and 'WgaTray.exe' in C:\WINDOWS\system32 folder by using the program Unlocker
seems to get rid of all the nags/popups.
Another alternative suggest that three files are installed Windows XP System Folder for WGA:
The wgatray.exe process makes the check for genuine windows software.
If WgaLogon.dll is denied execution right, that WinLogon is unable to
call it to check on Windows validity and display notification package at
boot, and since WgaLogon is also responsible for running and
maintaining WgaTray.exe, no more tray popups either.
To change and disable the execute bit of WgaLogon.dll:
Turn off Simple File Sharing in Tools -> Folder Options -> View tab.
Right click WgaLogon.dll in Windows Explorer and open the Security Tab.
Click Advanced button.
Uncheck the Inherit box at the bottom.
Click the Copy button.
Go through each listed user/group and remove the "Read & Execute"
permission for WgaLogon.dll, leaving the "Read" permission as-is.
Click OK to apply the permission changes.
Close the file properties dialog.
Restart the computer.
Turn "Use simple file sharing" on (optional).