You can get a lot of information about the system stuff from API calls. I would think that screen resolution would be one of them. Something that will at least give you the size of the screen, in Access measurements, where 1440 units = 1" would be this way.
Create a form with these properties:
..Scroll Bars: Neither
..Record Selectors: No
..Navigation Buttons: No
..Dividing Lines: No
..Border Style: None
..Control Box: No
..Min Max Buttons: None
..Close Button: No
Put this code in the Open Event:
.. DoCmd.Maximize
.. ScreenHeight = Me.WindowHeight
.. ScreenWidth = Me.WindowWidth
Put this code in the Timer Event:
.. DoCmd.Close acForm, Me.Name
Set the Timer Interval (on the "Event" tab within Form Properties)
.. To 500
This code will cause this form to fill the entire screen, then save the height and width into the two variables "ScreenHeight" and "ScreenWidth" (name them whatever you want and make them Global variables).
Then, depending on the size of the screen, you can change the size of your forms.
To change the size of a form, use the command DoCmd.MoveSize. The 3rd and 4th parameters to this command are Width and Height. This command will change only the active form unless you select another form with "DoCmd.SelectObject acForm, frmFormName, True". Be sure to change the "frmFormName" to your form's name. (Read the help associated with this command for more info.)
HTH,