Width is a property like Top and Height for controls.
The easiest way is to make a macro and use MoveSize action. When you select the MoveSize action you will see the items for Width, Right etc at the bottom. The number entered is either for Centimetres or Inches.
If you narrow the Width it will narrow from the right side of the form and thus the form will no longer be centred. To offset that you need to put a number in for Right.
This is one area (mainly with Vista) where I have found code to do the same thing to be unreliable, DB will sometimes lock up.
I was unaware of the TWIP thing. I actually needed to do the resizing because I wanted to switch a subform from SingleForm to DataSheet view and the DataSheet view was wider, but only to discover, now I can make the form wider on a command button click, but I can't change the view format of the subform. Oh well, I started a new thread for that. Thank again everyone!