rules editor/engine

Hi,

I recently entered into the realm of ontologies and there logic rules.  It seems that there is a lot of information in the web in this subject.  However, (or maybe: because of that) it is hard for me to reach any decision.

Can someone recommend of a good rules editor and/or a good rules engine.

Preferable:
* one that can read ontology that was created using protege.
* one that is based on first order logic

Thanks in advance,
  Avner