An archive folder is like any personal folder file. The default location of the file is: C:\Documents and Settings\username\Local Settings\Application Data\Microsoft\Outlook. From Outlook, click File, Open…Outlook data file…and then go to the path listed above. You should see an Archive.pst file.
The problem I see is that the Contact folder is not setup by default to be archived so I’m not sure if it will be in the archived pst file.