Do I need a DTV converter or a better antenna?

Im not sure if my TV is digital ready. I recently had my cable temporarily disconnected and I hooked up a pair of rabbit ears and I don't get big name channels life FOX, NBC, ABC and CBS but I receive the CW, QVC, Univision, Telemundo and a bunch of other spanish channels. Is it my generic antenna? I have a Mitsubishi 57" that I purchased almost 2 years ago. I did a channel search and it took 30 min. At the end it said now scanning digital channels but no results. So do I need to buy a DTV converter or a better antenna? Somebody help me please. I don't speak spanish but I rather watch the Spanish channels over the CW