"When you get a system installed Eclipse Nav... Do you get your old raido back?? Never had a system installed before so I guess I need to know if I should have gotten it back."
Regardless of whether this was a dealer or sound shop install, YOU OWNED the orginal factory radio.
Unless they gave you a credit on the install for the factory head, you should have gotten that radio back when you picked up the car. That would then give you the option to uninstall your upgrade and restore the factory radio if you chose to when selling (or sell it on SCOA).
That being said, today YOUR original factory radio is likely on eBay!