Hi David,
Look for the following configuration key:
Preferences\MainWindow\MaximizeAtStartup
and set it to false. In addition, you might also be interested in messing with these ones:
Preferences\MainWindow\FullScreenAtStartup
Preferences\MainWindow\ShowSplashAtStartup
For now, each time you install a new version, all configuration keys are restored to their default values, so you have to redo the manual editing work... This will change very soon with the new Preferences process/interface, and also a new command-line command that will allow you to edit preference keys individually.
Hope this helps.