The files etc. are stored in the OJS files path, which is configured in config.inc.php in the "files_dir" directive. For example, original submission files are stored in (files_path)/journals/(journal_id)/articles/(article_id)/submission/original/(article_id)_(file_id)_(revision).odt (or .doc, or .rtf, etc).
Open Journal Systems Team
Don't miss the First International PKP Scholarly Publishing Conference
July 11 - 13, 2007, Vancouver, BC, Canada