Whether you use the public defender or a private attorney, it's always a good idea to have a lawyer when charged with a crime.
While most defendants can, in theory, represent themselves, it's almost always a bad idea. Mounting a criminal defense requires a thorough knowledge of many very detailed laws, and knowing how judges have interpreted these rules in past cases. It's just as important to understand the human factor: how cases like yours are handled in your courthouse by the judges, prosecutors, and police who make discretionary decisions all the time. Only someone well-versed in the law and the local legal scene can adequately assess the strengths and weaknesses of a case and its chances in court or at the negotiating table.
Most people charged with a crime will qualify for the services of a court-appointed attorney (not because the system is so generous, but because demographically, most defendants are too poor to hire their own attorney). Those who do not qualify for appointed counsel will need to find and hire a lawyer. Follow the links below for information on the varying options for representation, and get some practical advice on making the choice.