I note some folk have had problems installing Omeka on a WAMP environment.
I got around the installation issues by installing the tables "elements" & "item_types" directly from the application/core/schema directory using phpmyadmin and removing them from the array $_defaultTables in application\models\Installer\Task\Schema.php.
This is for a development implementation (not the live site) and seems to be working fine.
I hope that helps someone.