Visual Basic - DESHABILITAR

Quisiera que me digan como puedo desabilitar los botones de minimizar,maximizar y cerrar en un formulario MDI

Sólo para win 9x

'Esto en un módulo
Public Declare Function GetSystemMenu Lib "user32" _
(ByVal hWnd As Long, ByVal bRevert As Long) As Long
Public Declare Function DeleteMenu Lib "user32" _
(ByVal hMenu As Long, ByVal nPosition As Long, _
ByVal wFlags As Long) As Long
Public Const SC_SIZE = &HF000
Public Const SC_MOVE = &HF010
Public Const SC_MINIMIZE = &HF020
Public Const SC_MAXIMIZE = &HF030
Public Const SC_CLOSE = &HF060
Public Const SC_RESTORE = &HF120
Public Const MF_SEPARATOR = &H800
Public Const MF_BYPOSITION = &H400
Public Const MF_BYCOMMAND = &H0

public sub ModifyMenu(byref hwnd as long, byval lParam as long)
hMenuH = GetSystemMenu(hwnd, 0)
Success = DeleteMenu(hMenuH, lParam, MF_BYCOMMAND)
end sub

'En el Form
Private sub Cambiar()
ModifyMenu me.hwnd,SC_MAXIMIZE
end Sub

Sólo para win 9x, en Win XP sólo funciona SC_CLOSE