Change the folder Outlook first opens to one of two ways:

1. Tools, Options, Other tab, Advanced button. Select a different folder using the browse button at the top of the page. Outlook 2003 supports any folder in your mailbox or personal stores (*.pst)
2. Create a desktop shortcut or enter the command line in Start Menu, Run.
   The command line will look like: Outlook.exe /select outlook:Calendar\New

Replace "calendar" with the folder name. If it returns an error use the full path to Outlook:
"C:\Program Files\Microsoft Office\Office10\Outlook.exe" /select outlook:calendar