The default Outlook PST File location can be located by using following tip :
Open the “Tree View” of your folders, if you haven’t already:
Each top level item, normally called “Personal Folders”, or “Outlook Today”, represents a separate PST. Right click on it and then select Properties:
Now click on the Advanced button:
And there, right in the middle of everything, is the Filename, the full path, to the PST. In this case you’ll notice that I’m most definitely using a non-standard location. Yours will most assuredly be different. The default location under Windows XP is typically a location underneath “\Documents And Settings\username”, where “username” is your Window login account name.