Access 2.0 was designed for 16 bit Windows 3.1. Since then all of the core DLLs changed so did all of the functions/subs they expose.
In your case you need to declare variable as Long. Also api function declarations are different - instead of Integers they return Long types as well as all of the arguments that used to be Integers must be Long.
VB Code:
Private Declare Function SetWindowText Lib "user32" _
Alias "SetWindowTextA" (ByVal hwnd As Long, _
ByVal lpString As String) As Long
Private Declare Function FindWindow Lib "user32" _
Alias "FindWindowA" (ByVal lpClassName As String, _
ByVal lpWindowName As String) As Long
Private Function SetCaption()
Dim hWnd [B]As Long[/B]
hWnd = FindWindow("OMain", 0&)
Call SetWindowText(hWnd, idsAPPNAME)
End Function
Note: % is the shortcut for Integer and Long is the &. Better way is to use the "As ..." when declaring variables.