You would rather get build number.
Build numbers simplify everything, Windows 7 build is 7600, SP1 version is 7601.
#define WinBuild "7600"
procedure GetSysInfo(var SysInfo: TSysInfo);
external 'GetSysInfo@files:Isab.dll stdcall delayload';
var SystemInfo: TSysInfo;
GetSysInfo(SystemInfo);
function CompreWindows:Boolean;
begin
Result:=SystemInfo.OSBuildNumbers>={#WinBuild};
end;
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