This two-part article addresses the issues concerning the building of new simulation software by either reusing existing general purpose software products and frameworks or by writing the simulation software from scratch. As a means of discussing the use of existing software, this first part describes a selected list of such existing software: the Eclipse IDE as graphical user front-end, Maven for the management and building of projects, Bonita for supporting simulation workflows, Ruby on Rails and its Hobo extension to provide online persistence, and the Fractal Component Model for supporting the popular Component-Based Modeling & Simulation approach. The second part, to be published in the next issue of M&S Magazine, will further explore some interesting features found in the selected software solutions, and discuss their benefits when applied to simulation.