1. A medical diagnostic system comprising: a computing environment arranged to receive patient information, comprising: a communications network; a server computer connected to the network; a client processor connected to the network and in data communication with the server computer via the network; an input device, connected to the client processor, to receive patient information from a user who is the patient or a proxy or assistant thereto; a script database; an output device, connected to the client processor, to provide information indicative of a diagnosed medical condition information; the environment executing programs for diagnosing by scoring a medical condition based on said patient information and communicating said diagnosed condition via said output device; said programs comprising: a plurality of medical complaint algorithms selectively executed based on at least a portion of the received information, wherein any one of the medical complaint algorithms scores at least a portion of the received information and diagnoses a medical condition associated with the executed medical complaint algorithm if the score reaches or passes a threshold; and wherein the program is arranged to read data from, and write data to, a medical history database stored in association with the client processor or said server computer, wherein any such scored information transferred between the client processor and the server computer is securely transmitted; and wherein each medical complaint algorithm is executed by said client processor, by a script engine program which is arranged: to interpret a medical complaint script file comprising lists of disease data, symptom data and question data; to output questions to said user; to input answers from said user via said input device; and to score said patient data and diagnose a said medical condition and update said medical history database using said scoring; and wherein said server computer is arranged to selectively download a said medical complaint script file to said client processor.