Reusable components

Hi, I have created on online scheduling system for a client. The system works well but is customized specifically for the client. Making changes and implementing the system for a different client would be a complicated task. I would like to know if its feasible to create classes of parts of the site I have made so I can implement them easily in future adaptations of a scheduling system. I have briefly studied the concepts of object oriented programming, but would appreciate anyone's input on the viability of such an approach. Thank you for your time.