Changes
→from wpkg package
The way this check works is that on Windows XP, wpkg would think that the package is already installed. This has a drawback: if you remove such a package, wpkg will try to remove this program every time on Windows XP systems, and then claim that the removal failed.
For more precise checks like Services Packs see also in ''HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion'' the ''ProductName'' and ''CSDVersion'' fields. There is an example in the [[Windows XP SP3]] silent installer.
===from batch file===