File > File Options...
under the tab 'Open/Close', in the section 'When opening this file', select "Perform Script"
Specify a script that uses a 'Go to Layout' script step
That's the way it works with Filemaker 9 as far as I can tell.
Instead of using the "Perform Script" step that obeechi suggested, you could just use the "Switch to layout" option in the same section.
Thanks Guys, (obeechi and mwc).