I just have a database without any ORM framework configured, can I still use objectWiz?
Yes! Using Hibernate Tools (available as an Eclipse plugin and Ant tasks), you can generate your mapping directly by reverse-engineering the database schema. We are planning to release a tutorial on how to do this soon.
What is the difference with existing database administration tools?
objectWiz is object-oriented! You work with objects and not tables/rows. Custom queries are carried-out with object-oriented interrogation languages such as HQL (Hibernate Query Language).