Try to follow these steps to migrate your
drupal site:
1. Copy all the files in the Drupal installation to the new location on the Linux server.
2. Make a SQL dump of the db on the Windows server.
3. Import the SQL dump on the Linux server.
4. Change the settings.php file to match the new database configuration.
5. Set permissions on files directory if needed.
Additionally, you might have to visit admin/config/media/file-system to fix the temporary dir setting.
That's more or less all he need to do if the Linux server is already configured, db created, virtual host configured etc.