No need to ask multiple times.
Outlook 2003 can display the Inbox and Calendar only in separate windows.
When viewing Inbox, right-click the Calendar folder and choose Open in New
Window. Tile the two windows as you wish. If you click File>Exit in the main
window without closing the second window, Outlook will remember you had both
windows open and reopen them both when you start it again.
For Outlook 2007 and later, you still don't have Inbox and Calendar in the
same window, you have the "To-Do Bar", which is a combination of your upcoming
events and your current tasks.