Free and good?
Generally these are mutually exclusive.
If anybody puts effort into making a good role playing game, they will charge money for it.
If you are absolutely opposed to putting out cash, I could only suggest RPG Maker.
There is a 2000 version and an XP version floating around.
You get it and then you find peoples homemade RPG's to plug into it.
Some of them are pretty darn good.