Looking for tools (windows platform) to genereate ER diagram (or similar) from an existing Oracle database.
Any good tools out there that are free to use or low cost?
Try out Oracle SQL Developer. It is from oracle and is going to be part of actual oracle installation from 11g onwards. It has a separate build modeler tool to engineer or re-engineer an ER model.
Other tool that may be useful that will help you more than just genereate ER diagram is SchemaSpy