Hoople - 7:52 pm on Aug 31, 2011 (gmt 0)
The PST location for Outlook varies slightly BY operating system and Outlook version.
On my Windows XP SP3 machine with Outlook 2007:
C:\Documents and Settings\USER_ID\Local Settings\Application Data\Microsoft\Outlook
PST's are 32kb by default on creation and will have a creation date that matches other files in that folder.
Search for *.pst as there might be archive.pst files located elsewhere.