Используя функции GetVersionEx и GetWindowsDirectory - VB

Private Declare Function GetWindowsDirectory Lib "kernel32" Alias "GetWindowsDirectoryA" (ByVal lpBuffer As String, ByVal nSize As Long) As Long
 
 
Private Sub Form_Load()
    
    Dim Path As String, strSave As String
    'Create a buffer string
    strSave = String(200, Chr$(0))
    'Get the windows directory
    Path = Left$(strSave, GetWindowsDirectory(strSave, Len(strSave)))
    MsgBox Path
End Sub