no impact on anything, i'm running WU. but, if U want impact, that would be [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion] "CSDVersion"="Service Pack 2" [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Windows] "CSDVersion"=dword:00000200 lets think WU or XPLite that U r on SP2, but that's another story :0) or SP4