Hi....
The above solution worked for me:
1. Restarted in safe mode->renamed SoftwareDistribution and Catroot2
2. Restarted in normal Mode-->click start, then run, then type in "regsvr32 -u %windir%\system32\legitcheckcontrol.dll"
3. Deleted the following files-->c:\windows\system32 directory and delete "legitcheckcontrol.dll".
4. Manually reinstall the latest version of WGA at http://go.microsoft.com/fwlink/?linkid=69498
Regards,
Ankita Narula
Microsoft Technical Support Team-XP