Como Saber se é Windows Vista?

uses 
  Windows 
... 

function WinVER: string; 
const 
  MS = ´Microsoft Windows ´; 
var 
  osVerInfo: TOSVersionInfo; 
begin 
  osVerInfo.dwOSVersionInfoSize := SizeOf(osVerInfo); 
  GetVersionEx(osVerInfo); 
  Result := ´´; 

  with osVerInfo do 
  begin 
    case dwPlatformId of 
    VER_PLATFORM_WIN32_WINDOWS: 
      case dwMinorVersion of 
        0: Result := MS + ´95´; 
        10: 
        if szCSDVersion[1] = ´A´ then 
          Result := MS + ´98 SE´ 
        else 
          Result := MS + ´98´; 
        90: Result := MS + ´ME´; 
      end; 

    VER_PLATFORM_WIN32_NT: 
      case dwMajorVersion of 
        3: Result := MS + ´NT 3.51 ´; 
        4: Result := MS + ´NT 4.0 ´ + szCSDVersion; 
        5: 
        case dwMinorVersion of 
          0: Result := MS + ´2000 ´ + szCSDVersion; 
          1: Result := MS + ´XP ´ + szCSDVersion; 
        end; 
        6: 
        case dwMinorVersion of 
          0: Result := MS + ´Vista ´ + szCSDVersion; 
        end; 
      end; 
    end; 
  end; 
  if Result = ´´ then 
    Result := ´Versão desconhecida do Windows .´; 
end; 

if (Win32Platform = VER_PLATFORM_WIN32_NT)
    and (Win32MajorVersion = 6) and (Win32MinorVersion = 0) then
begin
end;