Open Regedit and go to :
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Windows
Find CSDVersion Key
Legend:
100 (hex) means its SP1
200 (hex) means its SP2
300 (hex) means its SP3
Change CSDVersion from 300 to 200 and Restart
Install kb888111xp2.exe (Microsoft UAA Patch)
Change CSDVersion back to 300.
Restart