Use the SetWindowPos API:

Put this in a module:
Code:
Public Declare Function SetWindowPos Lib "user32" Alias "SetWindowPos" (ByVal hwnd As Long, ByVal hWndInsertAfter As Long, ByVal x As Long, ByVal y As Long, ByVal cx As Long, ByVal cy As Long, ByVal wFlags As Long) As Long

Public Const SWP_NOMOVE = &H2
Public Const SWP_NOSIZE = &H1

Public Const HWND_TOPMOST = -1

Public Sub MakeAlwaysOnTop(ByVal hWindow As Long)
    SetWindowPos hWindow, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE Or SWP_NOSIZE
End Sub
And this in the Form_Load() event:
Code:
Private Sub Form_Load()
    MakeAlwaysOnTop Me.hWnd
End Sub
Hope this helps.