Read szlammy's post. He explained it CLEARLY. 1440 twips per inch. If you change your screen resolution, that number will no longer be valid.
Twip = PixelNum& * screen.twipsperpixelx for horizontal and screen.twipsperpixely for vertical.
If you are using API, you can get the client area of your window with
Code:
Private Declare Function GetClientRect Lib "user32" (ByVal hWnd As Long, ByRef lpRect As RECT) As Long
where hwnd is the handle to your window
and you can convert form pixel position to screen pixel position with this:
Code:
Public Declare Function ClientToScreen Lib "user32" (ByVal hWnd As Long, lpPoint As POINTAPI) As Long
where as above hwnd is the handle to your form.
Both RECT and POINTAPI are structures defined in the api text browser.