Visual Basic - Cosas de API's

Hoooola y saludos a todos!!
Quisiera saber sialguien me puede decir que si estas API's con las funciones que tienen, se puedenencontrar en todos los sistemas WIndows, o solo en los NT?
Asi mismo que si un programa que utilize esas funciones puede funcionar en maquinas win 9x

Private Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Long) As Integer
Private Declare Function GetKeyState Lib "user32" (ByVal nVirtKey As Long) As Integer
Private Declare Function GetForegroundWindow Lib "user32" () As Long
Private Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" (ByVal hwnd As Long, ByVal lpString As String, ByVal cch As Long) As Long
Private Declare Function GetWindowTextLength Lib "user32" Alias "GetWindowTextLengthA" (ByVal hwnd As Long) As Long

GetAsyncKeyState = Requires Windows NT 3.1 or later; Requires Windows 95 or later
GetKeyState =Requires Windows NT 3.1 or later; Requires Windows 95 or later
GetForegroundWindow =Requires Windows NT 3.1 or later; Requires Windows 95 or later

GetWindowText = Requires Windows NT 3.1 or later; Requires Windows 95 or later
GetWindowTextLength = Requires Windows NT 3.1 or later; Requires Windows 95 or later

Fuente: AllAPINet